Electrophysiology catheter for mapping and/or ablation

ABSTRACT

The present invention encompasses apparatus and methods for mapping electrical activity within the heart. The present invention also encompasses methods and apparatus for creating lesions in the heart tissue (ablating) to create a region of necrotic tissue which serves to disable the propagation of errant electrical impulses caused by an arrhythmia.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. provisionalapplication serial No. 60/287,057, entitled “Handles For MedicalDevices,” filed Apr. 27, 2001, and U.S. provisional application serialNo. 60/345,119, entitled “Handle Thumb Wheel Mechanism Which MaintainsHolding Forces When Sterilized,” filed Oct. 19, 2001, which are herebyincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to electrophysiology catheters, andmore particularly to electrophysiology catheters for performingendocardial mapping and/or ablation procedures.

[0004] 2. Discussion of the Related Art

[0005] The human heart is a very complex organ, which relies on bothmuscle contraction and electrical impulses to function properly. Theelectrical impulses travel through the heart walls, first through theatria and then the ventricles, causing the corresponding muscle tissuein the atria and ventricles to contract. Thus, the atria contract first,followed by the ventricles. This order is essential for properfunctioning of the heart.

[0006] In some individuals, the electrical impulses of the heart developan irregular propagation, disrupting the heart's normal pumping action.The abnormal heartbeat rhythm is termed a “cardiac arrhythmia.”Arrhythmias may occur when a site other than the sinoatrial node of theheart is initiating rhythms (i.e., a focal arrhythmia), or whenelectrical signals of the heart circulate repetitively in a closedcircuit (i.e., a reentrant arrhythmia).

[0007] Techniques have been developed which are used to locate cardiacregions responsible for the cardiac arrhythmia, and also to disable theshort-circuit function of these areas. According to these techniques,electrical energy is applied to a portion of the heart tissue to ablatethat tissue and produce scars which interrupt the reentrant conductionpathways or terminate the focal initiation. The regions to be ablatedare usually first determined by endocardial mapping techniques. Mappingtypically involves percutaneously introducing a catheter having one ormore electrodes into the patient, passing the catheter through a bloodvessel and into an endocardial site, and deliberately inducing anarrhythmia so that a continuous, simultaneous recording can be made witha multichannel recorder at each of several different endocardialpositions. When an arrythormogenic focus or inappropriate circuit islocated, as indicated in the electrocardiogram recording, it is markedby various imaging or localization means so that cardiac arrhythmiasemanating from that region can be blocked by ablating tissue. Anablation catheter with one or more electrodes can then transmitelectrical energy to the tissue adjacent the electrode to create alesion in the tissue. One or more suitably positioned lesions willtypically create a region of necrotic tissue which serves to disable thepropagation of the errant impulse caused by the arrythromogenic focus.Ablation is carried out by applying energy to the catheter electrodes.The ablation energy can be, for example, RF, DC, ultrasound, microwave,or laser radiation.

[0008] Atrial fibrillation together with atrial flutter are the mostcommon sustained arrhythmias found in clinical practice.

[0009] Current understanding is that atrial fibrillation is frequentlyinitiated by a focal trigger from the orifice of or within one of thepulmonary veins. Though mapping and ablation of these triggers appearsto be curative in patients with paroxysmal atrial fibrillation, thereare a number of limitations to ablating focal triggers via mapping andablating the earliest site of activation with a “point” radiofrequencylesion. One way to circumvent these limitations is to determineprecisely the point of earliest activation. Once the point of earliestactivation is identified, a lesion can be generated to electricallyisolate the trigger with a lesion; firing from within those veins wouldthen be eliminated or unable to reach the body of the atrium, and thuscould not trigger atrial fibrillation.

[0010] Another method to treat focal arrhythmias is to create acontinuous, annular lesion around the ostia (i.e., the openings) ofeither the veins or the arteries leading to or from the atria thus“corralling” the signals emanating from any points distal to the annularlesion. Conventional techniques include applying multiple point sourcesaround the ostia in an effort to create such a continuous lesion. Such atechnique is relatively involved, and requires significant skill andattention from the clinician performing the procedures.

[0011] Another source of arrhythmias may be from reentrant circuits inthe myocardium itself. Such circuits may not necessarily be associatedwith vessel ostia, but may be interrupted by means of ablating tissueeither within the circuit or circumscribing the region of the circuit.It should be noted that a complete ‘fence’ around a circuit or tissueregion is not always required in order to block the propagation of thearrhythmia; in many cases simply increasing the propagation path lengthfor a signal may be sufficient. Conventional means for establishing suchlesion ‘fences’ include a multiplicity of point-by-point lesions,dragging a single electrode across tissue while delivering energy, orcreating an enormous lesion intended to inactivate a substantive volumeof myocardial tissue.

SUMMARY OF THE INVENTION

[0012] The present invention encompasses apparatus and methods formapping electrical activity within the heart. The present invention alsoencompasses methods and apparatus for creating lesions in the hearttissue (ablating) to create a region of necrotic tissue which serves todisable the propagation of errant electrical impulses caused by anarrhythmia.

[0013] According to one aspect of the present invention, anelectrophysiology catheter is provided. In one embodiment, the cathetercomprises a handle, a flexible shaft, a tip assembly, and a cable. Thehandle has a distal end and a proximal end and includes an actuator. Theflexible shaft has a proximal end and a distal end and a longitudinalaxis that extends along a length of the shaft, the proximal end of theshaft being attached to the distal end of the handle. The tip assemblyhas a proximal end and a distal end, the proximal end of the tipassembly being attached to the distal end of the shaft. The distal endof the tip assembly is biased in an arcuately curved shape having aradius of curvature. The cable is attached to the actuator and thedistal end of the tip assembly and extends through the shaft. The cableis adapted to change the radius of curvature of the distal end of thetip assembly in response to movement of the actuator.

[0014] According to another embodiment of the present invention, anelectrophysiology catheter is provided that comprises a handle, aflexible shaft, a tip assembly, and a cable. The handle has a distal endand a proximal end and includes an actuator. The flexible shaft has aproximal end and a distal end and a longitudinal axis that extends alonga length of the shaft, the proximal end of the shaft being attached tothe distal end of the handle. The tip assembly has a proximal end and adistal end, the proximal end of the tip assembly being attached to thedistal end of the shaft. The proximal end of the tip assembly includes afixed bend of approximately ninety degrees relative to the longitudinalaxis of the shaft, and the distal end of the tip assembly includes anarcuate curve having a diameter, the arcuate curve being oriented in aplane that is approximately perpendicular to the longitudinal axis ofthe shaft. The cable is attached to the actuator and the distal end ofthe tip assembly and extends through the shaft. The cable is adapted tochange the diameter of the arcuate curve in response to movement of theactuator.

[0015] According to another embodiment of the present invention, anelectrophysiology catheter is provided that comprises a handle, aflexible shaft, a tip assembly, and first and second cables. The handlehas a distal end and a proximal end and includes a first actuator and asecond actuator. The flexible shaft has a proximal end and a distal endand a longitudinal axis that extends along a length of the shaft, theproximal end of the shaft being attached to the distal end of thehandle. The tip assembly has a proximal end and a distal end, theproximal end of the tip assembly being attached to the distal end of theshaft and the distal end of the tip assembly being biased in anarcuately curved shape and having a radius of curvature. The first cableis attached to the first actuator and the proximal end of the tipassembly and extends through the shaft. The first cable is adapted tobend the distal end of the tip assembly so that the distal end of thetip assembly is approximately perpendicular to the longitudinal axis ofthe shaft in response to movement of the first actuator. The secondcable is attached to the second actuator and the distal end of the tipassembly and extends through the shaft. The second cable is adapted tochange the radius of curvature of the distal end of the tip assembly ina plane that is approximately perpendicular to the longitudinal axis ofthe shaft in response to movement of the second actuator.

[0016] According to another aspect of the present invention, a handle isprovided for use with a catheter. In one embodiment the catheter has anelongated shaft and a tip assembly attached to a distal end of theelongated shaft. The shaft has a longitudinal axis that extends along alength of the shaft, and the tip assembly includes at least one cablefor changing at least one of a shape of the tip assembly and anorientation of the tip assembly relative to the longitudinal axis of theshaft. The handle comprises a housing and an actuator that is disposedon the housing. The actuator is attached to the at least one cable andmovable between a first position defining one of a first shape of thetip assembly and a first orientation of the tip assembly relative to thelongitudinal axis of the shaft and a second position defining one of asecond shape of the tip assembly and a second orientation of the tipassembly relative to the longitudinal axis of the shaft. The handlefurther comprises frictional means for imparting a first amount offriction on the at least one cable in the first position and forimparting a second amount of friction on the at least one cable when theactuator is moved away from the first position, the second amount offriction being greater than the first amount of friction.

[0017] According to another embodiment of the present invention, ahandle for use with a catheter having a proximal end and a distal end isprovided. The catheter includes at least one cable for moving a portionof the distal end of the catheter between a first position and a secondposition relative to the proximal end of the catheter. The handlecomprises a housing, an actuator disposed on the housing, the actuatorbeing attached to the at least one cable and movable between a thirdposition and a fourth position. The third position of the actuatorcorresponds to the first position of the portion of the distal end ofthe catheter relative to the proximal end of the catheter, and thefourth position corresponds to the second position of the portion of thedistal end of the catheter. The handle further includes frictional meansfor imparting a first amount of friction on the actuator when theactuator is in the third position and for imparting a second amount offriction on the actuator when the actuator is moved away from the thirdposition, the second amount of friction being greater than the firstamount of friction.

[0018] According to another aspect of the present invention, a handlefor use with a catheter having an elongated shaft and a tip assemblyattached to a distal end of the elongated shaft is provided. The shafthas a longitudinal axis that extends along a length of the shaft, andthe tip assembly includes at least one cable for changing a radius ofcurvature of a distal end of the tip assembly. The handle comprises ahousing, an actuator disposed on the housing, the actuator beingattached to the at least one cable and movable between a first positiondefining a first radius of curvature of the distal end of the tipassembly and a second position defining a second radius of curvature ofthe distal end of the tip assembly, and graphical indicia indicative ofthe radius of curvature of the distal end of the tip assembly when theactuator is in at least one of the first position and the secondposition.

[0019] According to a further aspect of the present invention, a handlefor use with a catheter having an elongated shaft and a tip assemblyattached to a distal end of the elongated shaft is provided. The shafthas a longitudinal axis that extends along a length of the shaft, andthe tip assembly includes at least one cable for changing a radius ofcurvature of a distal end of the tip assembly. The handle comprises ahousing, an actuator disposed on the housing, the actuator beingattached to the at least one cable and movable between a first positiondefining a first radius of curvature of the distal end of the tipassembly and a second position defining a second radius of curvature ofthe distal end of the tip assembly, and a plurality of protrusions,disposed on at least one of the housing and the actuator, to providetactile feedback to a user when the actuator is moved from the firstposition.

[0020] According to another aspect of the present invention, a method ofshaping a distal end of a catheter is provided. The method comprisesacts of placing the distal end of the catheter in a jig, maintaining thedistal end of the catheter and the jig at a predetermined temperaturefor a predetermined time, and removing the distal end of the catheterfrom the jig. The jig includes a passageway to receive the distal end ofthe catheter and hold the distal end of the catheter in a fixedposition. The passageway defines three contiguous regions including afirst straight region formed in a first plane, a second curved region inwhich the passageway bends within the first plane approximatelyperpendicularly to the first straight region, and a third curved regionin which the passageway curves arcuately in a second plane that isperpendicular to the first plane.

[0021] According to another aspect of the present invention, a jig forshaping a distal end of a catheter is provided. The jig comprises amandrel having a passageway to receive the distal end of the catheter,and a retainer removably attached to the mandrel to hold the distal endof the catheter within the passageway. The passageway defines threecontiguous regions including a first straight region formed in a firstplane, a second curved region in which the passageway bends within thefirst plane approximately perpendicularly to the first straight region,and a third curved region in which the passageway curves arcuately in asecond plane that is perpendicular to the first plane.

[0022] According to another aspect of the present invention, a method ofusing a catheter is provided. The catheter includes a handle, a flexibleshaft having a longitudinal axis, and a tip assembly, the shaft beingconnected between the handle and the tip assembly. A distal end of thetip assembly includes an arcuate curve having a diameter. The methodcomprises acts of placing the tip assembly inside a heart of a patient,and remotely, from outside the patient, adjusting the diameter of thearcuate curve.

[0023] According to another embodiment, a method of using a catheter isprovided. The catheter includes a handle, a flexible shaft having alongitudinal axis, and a tip assembly. The shaft is connected betweenthe handle and the tip assembly. A proximal end of the tip assemblyincludes a fixed bend of approximately ninety degrees relative to thelongitudinal axis of the shaft, and the distal end of the tip assemblyincludes an arcuate curve having a diameter, the arcuate curve beingoriented in a plane that is approximately perpendicular to thelongitudinal axis of the shaft. The method comprises acts of placing thedistal end of the tip assembly inside a heart of a patient so that thearcuate curve of the distal end of the tip assembly contacts an innersurface of a heart vessel, and remotely, from outside the patient,applying a radially outward pressure with the distal end of the tipassembly against the inner surface of the heart vessel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Illustrative, non-limiting embodiments of the present inventionare described by way of example with reference to the accompanyingdrawings, in which:

[0025]FIG. 1 illustrates a schematic view of a mapping and/or ablationcatheter system in accordance with the present invention;

[0026]FIG. 2 is an end elevational view of a distal end tip assembly,taken along line 2-2 in FIG. 1, that may be used with the cathetersystem of FIG. 1 according to one embodiment of the present invention;

[0027]FIG. 3 is a perspective view of the distal end tip assembly ofFIG. 2;

[0028]FIG. 4 is an alternative perspective view of the distal end tipassembly of FIG. 2 illustrating the manner in which the radius ofcurvature of the distal end may be changed;

[0029]FIG. 5 illustrates a first jig that may be used to impart a fixedshape to the distal end tip assembly according to one embodiment of thepresent invention;

[0030]FIG. 6 illustrates a side elevational view of the jig of FIG. 5;

[0031]FIG. 7 is a cross sectional side view of a second jig that may beused to impart a fixed shape to the distal end tip assembly according toanother embodiment of the present invention;

[0032]FIG. 8 is an exploded perspective view of the jig of FIG. 7;

[0033]FIG. 9 is a cross sectional side view of a third jig that may beused to impart a fixed shape to the distal end of the tip assemblyaccording to another embodiment of the present invention;

[0034]FIG. 10 is an exploded perspective view of the jig of FIG. 9;

[0035]FIG. 11 is an enlarged end elevational view of the distal end tipassembly of FIG. 2;

[0036]FIG. 12 is a schematic view of the distal end tip assembly of FIG.11 in a tightly coiled position;

[0037]FIG. 13 is a schematic view of the distal end tip assembly of FIG.11 in a loosely coiled position;

[0038]FIG. 14 is a side elevational view of the distal end of a finishedcatheter prior to shaping with any one of the jigs of FIGS. 5-10;

[0039]FIG. 15 is a cross sectional view of the distal end of thecatheter of FIG. 14 taken along line 15-15 in FIG. 14;

[0040]FIG. 15A is a fragmentary cross sectional view of the distal endof the catheter of FIG. 15 showing an alternative raised profileelectrode;

[0041]FIG. 16 is a cross sectional view of the distal end of thecatheter of FIG. 15 taken along line 16-16 in FIG. 15;

[0042]FIG. 17 is a cross sectional view of the distal end of thecatheter of FIG. 15 taken along line 17-17 in FIG. 15;

[0043]FIG. 18 is a perspective view of a distal end tip assemblyaccording to another embodiment of the present invention that may beused with the catheter system of FIG. 1, and which includes a slidingelectrode;

[0044]FIG. 19 is a cross sectional side view of the distal end tipassembly of FIG. 18 taken along line 19-19 in FIG. 18;

[0045]FIG. 20 is a cross sectional end view of the distal end of tipassembly of FIG. 19 taken along line 20-20 in FIG. 19;

[0046]FIG. 21 is a perspective view of a distal end tip assemblyaccording to another embodiment of the present invention that may beused with the catheter system of FIG. 1;

[0047]FIG. 21A is a cross sectional view of the distal end tip assemblyof FIG. 21 taken along line 21A-21A in FIG. 21;

[0048]FIG. 22 is an exploded view of a handle, taken along line 22-22 inFIG. 1, that may be used with the catheter system of FIG. 1 according toanother embodiment of the present invention;

[0049]FIG. 23 is a schematic cross sectional view of a slide actuatorfor the handle of FIG. 22 in a neutral or unloaded state;

[0050]FIG. 24 is a schematic cross sectional view of a slide actuatorfor the handle of FIG. 22 in a deployed or loaded state;

[0051]FIG. 25 is a cross sectional end view of the slide actuator ofFIG. 23 taken along line 25-25 in FIG. 23;

[0052]FIG. 26 is an exploded perspective view of the left section of thehandle of FIG. 22;

[0053]FIG. 27 is a schematic cross sectional view of a thumbwheelactuator for the handle of FIG. 22 in a neutral or unloaded state;

[0054]FIG. 28 is a schematic cross sectional view of the thumbwheelactuator for the handle of FIG. 22 in a deployed or loaded state;

[0055]FIG. 29A is an elevational view of another handle that may be usedwith the catheter system of FIG. 1 according to another embodiment ofthe invention that includes a third actuator;

[0056]FIG. 29B is a schematic view of another handle according toanother embodiment of the invention that includes a plunger-type thirdactuator;

[0057]FIG. 30 is a side elevational view of a handle that may be usedwith the catheter system of FIG. 1 and which includes features thatprovide tactile feedback to a user when using one of the actuators;

[0058]FIG. 31 is a schematic cross sectional view of one implementationfor providing tactile feedback to a user that is adapted for use withthe slide actuator of FIG. 30;

[0059]FIG. 32 is a schematic cross sectional view of anotherimplementation for providing tactile feedback to a user that is alsoadapted for use with the slide actuator of FIG. 30;

[0060]FIG. 33 is a side elevational view of an handle that includesgraphical indicia indicative of a radius of curvature of the distal endtip assembly according to another embodiment of the present invention;

[0061]FIG. 34 is a side elevational view of a distal end tip assemblyaccording to another embodiment of the present invention that includes alocalization sensor and a temperature sensor;

[0062]FIG. 35 illustrates the insertion of a catheter of the presentinvention into a body of a patient;

[0063]FIG. 36 illustrates the insertion of the catheter of the presentinvention into a heart; and

[0064]FIG. 37 illustrates the insertion of the distal end of thecatheter into the ostium of a pulmonary vein in the heart.

DETAILED DESCRIPTION

[0065] In this description, various aspects and features of the presentinvention will be described. One skilled in the art will appreciate thatthe features may be selectively combined in a device depending on theparticular application. Furthermore, any of the various features may beincorporated in a catheter and associated method of use for mappingand/or ablation procedures.

[0066] Catheter Overview

[0067] Reference is now made to FIG. 1, which illustrates an overview ofa mapping and/or ablation catheter system for use in electrophysiologyprocedures, in accordance with the present invention. The systemincludes a catheter 100 having a flexible shaft 110, a control handle120, and a connector 130. When used in mapping applications, theconnector 130 is used to allow signal wires running from mappingelectrodes at a distal end of the catheter 100 to be connected to adevice for recording signals, such as a recording device 160. When usedin ablation applications, connector 130 is used to allow signal wiresrunning from ablation electrodes at the distal end of the catheter 100to be connected to a device for generating ablation energy, such asablation energy generator 170. As will be described further in detailbelow, the distal end of the catheter 100 may include separate mappingand/or ablation electrodes, or may alternatively include electrodes thatare adapted for both mapping and ablation.

[0068] A controller 150 is electrically connected to connector 130 viacable 115. In one embodiment, controller 150 may be a QUADRAPULSE RFCONTROLLER™ device available from C. R. Bard, Inc., Murray Hill, N.J.Ablation energy generator 170 may be connected to controller 150 viacable 116. Recording device 160 may be connected to controller 150 viacable 117. When used in an ablation application, controller 150 is usedto control ablation energy, provided by ablation energy generator 170,to catheter 100. When used in a mapping application, controller 150 isused to process signals from catheter 100 and provide these signals torecording device 160. Although illustrated as separate devices,recording device 160, ablation energy generator 170, and controller 150may be incorporated into a single device. It should further beappreciated that although both ablation energy generator 170 andrecording device 160 are illustrated in FIG. 1, either or both of thesedevices may be incorporated in the catheter system in accordance withthe present invention.

[0069] The shaft 110 of the catheter 100 is, in one embodiment,approximately six French in diameter, although it should be appreciatedthat many diameters are possible, and the diameter of shaft 110 may besmaller or larger depending on the particular application and/orcombination of features incorporated into the catheter 100. Attached toa distal end 112 of the shaft 110 is a distal end tip assembly 140having a proximal end 142 that is attached to the distal end 112 of theshaft 110, and a distal end 144 having one or more electrodes 146 (SeeFIG. 2). The length of the tip assembly 140 may be approximately 7 to 8cm in length, although other lengths may be suitably employed, as thepresent invention is not limited to any particular length. Further, andas will be subsequently described, the number and placement ofelectrodes along the distal end 144 of the tip assembly 140 may varydepending upon the application. For example, for mapping applications, aplurality of low profile electrodes may be preferred, whereas forablations applications a lesser number of higher profile electrodes maybe preferred. Embodiments of the present invention may include as few asone electrode, which may be movably attached to the distal end 144 ofthe tip assembly 140, or may alternatively include a plurality of fixedelectrodes, for example 20 or more, spaced apart along the distal end142 of the tip assembly 140. Further, the construction of the electrodeor electrodes 146 may vary, as known to those skilled in the art.

[0070] According to one aspect of the present invention, and as shown indetail in FIG. 3, the proximal end 142 of the tip assembly 140 includesan approximately ninety degree bend 148 relative to a longitudinal axis(L) of the shaft 110, which may be active, or fixed, and the distal end144 of the tip assembly 140 includes an arcuate curve that is orientedorthogonally to the longitudinal axis of the shaft 110. As used inassociation with the approximately ninety degree bend 148, the term“active” is herein defined to mean that the portion of the proximal end142 of the tip assembly 140 where the bend 148 is formed is capable ofmovement, relative to the longitudinal axis (L) of the shaft 110 betweenapproximately zero degrees and approximately ninety degrees viamanipulation of a remotely controlled actuator (e.g., actuators 122, 124disposed on the handle 120). The term “fixed,” as used in associationwith the approximately ninety degree bend 148, is herein defined to meanthat the approximately ninety degree bend 148 is permanently formed inthe proximal end 142 of the tip assembly 140, such that theapproximately ninety degree bend retains its shape at body temperatures.

[0071] According to a further aspect of the present invention, theradius (or alternatively, the diameter) of curvature of the arcuatelycurved distal end 144 may be adjustable by operation of an actuator(e.g., actuators 122, 124) disposed on the handle 120. The combinationof the approximate ninety degree bend followed by an arcuate curve thatis adjustable in diameter permits the catheter 100 to be uniquely suitedfor mapping and/or ablation procedures in difficult endocardial sites,such as, for example, within a blood vessel, such as a pulmonary vein,or an ostium of a blood vessel, such as the ostium of a pulmonary vein.For example, in both mapping and ablation procedures, the approximatelyninety degree bend permits pressure, applied to the handle 120, to betranslated to the distal end 144 of the tip assembly 142, to therebyurge the distal end 144 of the tip assembly 140 tight against theendocardial site. The adjustible radius of curvature of the arcuatecurve can be used to apply an outwardly radial pressure to further forcethe distal end 144 of the tip assembly 140 tight against the endocardialsite, or to adjust to endocardial sites of different diameters (e.g.that of an adult or large animal, or a small child or small animal), orboth. This ability to urge the distal end 144 of the tip assembly tightagainst an endocardial site is advantageous in mapping procedures tobetter localize the source of the cardiac arrhythmia, and may be used inablation procedures to focus the ablation energy on the selectedendocardial site. Further, because the radius of curvature of the distalend 144 of the tip assembly can be adjusted to different diameters, thecatheter may be used with either an adult (or large animal) or a child(or small animal), as “one size fits all.” This ability to accommodate arange of sizes can reduce the number of distinctly sized catheters thatneed to be stocked by the manufacturer or the care provider.

[0072] Disposed on the handle 120 are one or more actuators 122, 124that may be used for a variety of purposes. Each of the actuators 122,124 is mechanically coupled to at least one cable that extends to thetip assembly 140 and which may be used to change the shape, orientation,or both the shape and orientation of the tip assembly. In the embodimentdepicted in FIG. 1, the handle 120 includes two different actuators, athumbwheel actuator 122 and a slide actuator 124. In one embodiment, thethumbwheel actuator 122 may be used to change the orientation of the tipassembly 140 in two opposing directions, and the slide actuator 124 maybe used to enlarge and decrease the radius of curvature of the arcuatelycurved distal end 144 of the tip assembly 140. As will be described indetail further below, the operation of the actuators 122, 124 may bereversed, such that the thumbwheel actuator 122 is used to control theradius of curvature, and the slide actuator 124 is used to control theorientation of the tip assembly 140 relative to the shaft 110 (e.g., toprovide steering). Moreover, as described further in detail below, thepresent invention is not limited to two distinct control actuators, asembodiments of the present invention may include only a single actuatorthat controls only one degree of movement (for example, increasing theradius of curvature of the arcuately curved distal end 144), or mayinclude several actuators, each capable of controlling two degrees ofmovement.

[0073] The Tip Assembly

[0074]FIGS. 2-4 illustrate a distal end tip assembly according to oneembodiment of the present invention. According to this embodiment, theproximal end 142 of the tip assembly 140 includes an approximatelyninety degree bend 148 relative to the longitudinal axis of the shaft110, followed by an arcuately curved distal end 144. In the embodimentdepicted in FIGS. 2-4, the approximately ninety degree bend 148 isfixed, that is, permanently formed in the proximal end 142 of the tipassembly 140, such that the approximately ninety degree bend 148 retainsits shape at body temperatures. In other embodiments, the approximatelyninety degree bend 148 may be active, that is, movable betweenapproximately zero and approximately ninety degrees relative to thelongitudinal axis (L) of the shaft 110 via a pull or push cable attachedto one of the actuators 122, 124 on the handle 120, as described furtherbelow with respect to FIG. 21.

[0075] In each embodiment, the region of the tip assembly 140 thatincludes the approximately ninety degree bend 148 is preferably biasedin a curved position relative to the longitudinal axis (L) of the shaft110, although the degree of bias may vary. Specifically, in embodimentsfeaturing a fixed bend, the bend 148 is permanently formed in theproximal end 142 of the tip assembly 140 at an angle of approximatelyninety degrees, such that while capable of being straightened forintroduction into a vessel, such as for example, through the use of asheath/dilator, the distal end 144 of the tip assembly 140 springs backin its unrestrained state to rest in a plane that is approximatelyperpendicular to the longitudinal axis (L) of the shaft 110. Inembodiments featuring an active bend, only a slight amount of bend, forexample, a few degrees, is permanently formed in the proximal end 142 ofthe tip assembly 140. This slight amount of bend in the proximal end 142of the tip assembly 140 is sufficient to ensure that the distal end 144of the tip assembly 140 bends in a predetermined direction relative tothe longitudinal axis (L) of the shaft 110, as described more fullybelow. However, in all embodiments, the distal end 144 of the tipassembly 140 is permanently biased in an arcuate shape to facilitateincreases and/or decreases in the radius of curvature of the distal end144 of the tip assembly 140 in a known and controlled manner.

[0076] Disposed on the arcuately curved distal end 144 of the tipassembly 140 are a plurality of ring-shaped electrodes 146 spaceduniformly apart along the distal end 144 and a distal end tip electrode147. Although illustrated as being uniformly spaced apart on the distalend 144 of the tip assembly 140, the electrodes 146 may alternatively begrouped in pairs, with the distance between each electrode of a pairbeing closer than the distance between electrodes of adjacent pairs. Forexample, each ring electrode may be approximately 1 mm in length, withpairs of electrodes being spaced approximately 2 mm apart on center, andwith electrodes of adjacent pairs being spaced apart by approximately 8mm. Furthermore, although the electrodes 146 illustrated in FIG. 2 areshown as being low profile ring electrodes that conform to the surfaceof the distal end 144 of the tip assembly 140, they may also be raisedin profile. Indeed, as described further in detail below, embodiments ofthe present invention may be used with any type of electrode that issuitable for use in endocardial or epicardial mapping and/or ablationprocedures, as the present invention is not limited to the number, theconstruction, or placement of electrodes on the distal end 144 of thetip assembly 140.

[0077] According to an embodiment of the present invention, the tipassembly 140 may be made from an elastomeric or polymeric thermodynamicbio-compatible material, such as PEBAX, that is bonded onto the distalend 112 of the flexible shaft 110, which may also be made from anelastomeric or polymeric thermodynamic bio-compatible material. Examplesof materials that may be used to form the flexible shaft 110 and the tipassembly 140 are well known in the art, and are described, for example,in commonly assigned U.S. Pat. Nos. 5,383,852, 5,462,527, and 5,611,777,which are hereby incorporated by reference in their entirety.

[0078] According to one embodiment of the present invention the flexibleshaft 110 may be made from a material that is stiffer than the materialused to form the proximal end 142 of the tip assembly 140, and the tipassembly 140 may be formed from a variety of bio-compatible materialsthat have different degrees of stiffness. For example, in oneembodiment, the flexible shaft 110 is made from a material having ahardness of approximately 60 Shore D, the proximal end 142 of the tipassembly is made from a material having a hardness of approximately45-50 Shore D, and the arcuately curved distal end 144 is made from amaterial having a hardness of approximately 40 Shore D. The increasedstiffness of the shaft 110 permits pressure applied to the handle 120 tobe more directly translated to the tip assembly 140. Further, theintermediate stiffness of the proximal end 142 of the tip assembly 140permits movement (i.e., steering) of the tip assembly 140 (describedfurther below) while ensuring that pressure applied to the handle 120 istranslated via the shaft 110 to the distal end 144 of the tip assembly140 to urge the distal end 144 of the tip assembly 140 tight against anendocardial site. Such enhanced contact is advantageous in both mappingand ablation procedures. Further, the relative flexibility of thematerial from which the distal end 144 of the tip assembly 140 is formedpermits the diameter of the arcuately curved distal end 144 of the tipassembly 140 to be changed (increased, decreased, or both) viamanipulation of one of the actuators 122, 124 on the handle 120. Inanother embodiment, the flexible shaft 110 is made from a materialhaving the same degree of hardness as the proximal end 142 of the tipassembly, for example, 45050 Shore D, but the flexible shaft 110 has alarger diameter, and is thus stiffer than the proximal end 142.

[0079] To further enhance contact with the endocardial site, theproximal end 142 of the tip assembly 140 may be stiffened, for examplewith an outer stiffening tube (not shown), just ahead (i.e., proximally)of the approximately ninety degree bend 148. For example, where the tipassembly 140 includes a fixed bend of approximately ninety degrees, thematerial forming the approximately ninety degree bend 148 may besufficiently stiffer than that from which the distal end 144 is formed,to further enhance contact with an endocardial or epicardial site.

[0080] Although embodiments of the present invention are not limited toany particular length, in one embodiment of the present invention, thelength of the flexible shaft is approximately one meter, the length ofthe proximal end 140 of the tip assembly is approximately 4.5 cm, thelength of the distal end 144 of the tip assembly is approximately 6.5cm, and the length of the approximately ninety degree bend portion isapproximately 0.7 cm. It should of course be appreciated that lengths ofthe different portions of the catheter may be varied, dependent upon theendocardial or epicardial site of interest.

[0081] As shown in FIG. 3, the tip assembly 140 may be movable (i.e.,steerable) in one or more directions perpendicular to the longitudinalaxis of the shaft 110. For example, as illustrated in the embodiment ofFIG. 3, the tip assembly 140 is capable of movement in two oppositedirections (shown as the Z axis) relative to the longitudinal axis ofthe shaft via manipulation of one of the actuators 122, 124 on thehandle 120 (FIG. 1). In other embodiments, the tip assembly may be movedin only a single direction (e.g., in the positive Z direction), or in anumber of different directions (e.g., in the positive and negative Zdirections, and the positive and negative Y directions).

[0082] As also shown in FIG. 3, and according to one aspect of thepresent invention, the radius (or alternatively, the diameter) ofcurvature of the arcuately curved distal end 144 of the tip assembly 140may be changed from a first diameter D1 to a second diameter D2.Preferrably, the radius of curvature of the arcuately curved distal end144 of the tip assembly 140 may be increased and decreased viamanipulation of one of the actuators 122, 124 disposed on the handle120. This ability to both increase and decrease the radius of curvatureof the distal end 144 of the tip assembly 140 permits a single tipassembly 140 to be used in a wide variety of applications and with awide variety of patients (from adults or large animals to children orsmall animals), as it can be adjusted to different diameters to suit therequirements of the patient and the particular medical procedure. Italso permits a radially outward force, or alternatively, a radiallyinward force, to be applied to an endocardial or epicardial site.

[0083] According to one embodiment of the present invention, thediameter of the arcuately curved distal end of the tip assembly isapproximately 20 mm in a resting state (corresponding to a neutralposition of the actuator 122, 124 that controls the radius of curvatureof the distal end 144 of the tip assembly 140), but may be decreased toa diameter of approximately 5 mm and increased to a diameter ofapproximately 50 mm via manipulation of one of the actuators 122, 124.According to this embodiment, the diameter of approximately 20 mmcorresponds to an approximately closed circle shown in FIGS. 2 and 3.The diameter of approximately 50 mm corresponds approximately to asemicircle, shown in phantom in FIG. 3, and the diameter ofapproximately 5 mm corresponds to more than one complete circle (i.e., aspiraling of the distal end) as shown in FIG. 4. Although the presentinvention is not limited to any particular diameter for the distal end144 of the tip assembly 140, these dimensions permit the catheter 100 tobe well suited for use in mapping and/or ablation procedures relating toblood vessels where focal triggers may be present, such as a pulmonaryvein. For example, a diameter of approximately 5 to 50 mm permits thetip assembly to be used for mapping and/or ablation procedures relatingto the ostium of a pulmonary vein where focal triggers for cardiacarrythmias may frequently be encountered. These dimensions also permit asingle tip assembly 140 to be used in either large or small humans oranimals, and for a wide variety of different procedures. It should beappreciated that the above-described dimensions for the diameter of thearcuately curved distal end of the tip assembly correspond to a radiusof curvature that is one half that of the indicated diameter (i.e., adiameter of 50 mm corresponds to a radius of curvature of 25 mm, etc.).

[0084] Although the radius of curvature of the distal end 144 of the tipassembly 140 described with respect to FIG. 3 is preferably capable ofbeing increased or decreased, the present invention is not so limited.For example, in certain embodiments, the radius of curvature may bechanged in only first direction (e.g., increased), while in otherembodiments, the radius of curvature may only be changed in a seconddirection (e.g., decreased). However, in each of the above describedembodiments, the distal end 144 of the tip assembly 140 is preferablypermanently biased into an arcuate shape in its resting state so thatthe increase and/or decrease in the radius of curvature is achieved in aknown and controlled manner.

[0085] Steering and Control of the Tip Assembly

[0086]FIG. 11 is an enlarged end elevational view of the distal end tipassembly 140 of FIG. 2. As shown in FIG. 11, in one embodiment of thepresent invention, the distal end 144 of the tip assembly 140 includes apair of cables 110 a, 1110 b that may be used to change the radius (oralternatively, the diameter) of curvature of the distal end 144 of thetip assembly from a first diameter to a second diameter. In theembodiment illustrated in FIG. 11, the tip assembly includes a core 1120that includes a plurality of lumens, including a central lumen 1125, andfour coaxial lumens 1128 a-d disposed about the central lumen 1125. Thecentral lumen 1125 is used to hold one or more electrically conductivewires (not shown in FIG. 11) that are attached to respective electrodes146, 147 disposed along the distal end 144 of the tip assembly 140. Thefour coaxial lumens 1128 a-d may be used to hold cables that control theorientation of the tip assembly 140 relative to the shaft 110, and thatcontrol the radius of curvature of the distal end 144 of the tipassembly 140. As illustrated in FIG. 11, two cables 110 a and 110 bextend along the length of the distal end 144 of the tip assembly 140,while the two other cables (not shown) terminate prior to the distal end144. In the embodiment depicted in FIG. 11, the ends of the two cables110 a and 1110 b are tied together and potted with an epoxy adjacent themost distal end of the tip assembly 140. In this embodiment, the cables1110 a and 110 b are used to control the radius of curvature of thedistal end 144 of the tip assembly 140.

[0087] Although the tip assembly is described as including a core 1120that includes a plurality of lumens 1125 and 1128 a-d, it should beappreciated that the tip assembly may be constructed in other ways. Forexample, U.S. Pat. Nos. 5,383,852, 5,462,527, and 5,611,777 describealternative constructions for the distal end of a catheter, some ofwhich include a central lumen that holds both the electrode wires andthe pull cables.

[0088] This alternative construction of the distal end tip assembly mayalso be used with embodiments of the present invention, as the presentinvention is not limited to any particular construction.

[0089]FIGS. 12 and 13 illustrate how the radius of curvature of thedistal end 144 of the tip assembly 140 may be changed via manipulationof the cables 1110 a, 1110 b that are attached to one or more of theactuators 122, 124 on the handle 120 (FIG. 1). In the embodimentillustrated, cables 1110 a and 1110 d are pull cables that may beformed, for example, from stainless steel wire or any other suitablematerial. Where the catheter 100 is to be used in an environment wherelarge magnetic fields may be present, for example, in an MRI chamber,each of the cables (and indeed, the electrodes 146, 147) may be madefrom non-ferromagnetic materials. For example, the electrodes may bemade from electrically conductive non-ferromagnetic materials such asplatinum, silver, or gold, while the cables may be made from compositematerials, such as carbon fiber, or KEVLAR™, or a multiplicity ofultra-high molecular weight polyethelene filaments. It should beappreciated that the cables 1110 a and 1110 b may alternatively be usedas push cables, although the use of push cables generally requires amore rigid and oftentimes larger diameter cable than that required for apull cable, which is operative under tension, rather than compression.As an example, the diameter of the pull cables may be in the range of0.003 to 0.004 inches.

[0090] As shown in FIGS. 12 and 13, tension applied to cable 1110 bresults in a decrease in the diameter of curvature of the distal end 144of the tip assembly 140 (and a corresponding slack in the cable 1110 a),while tension applied to cable 110 a results in an increase in thediameter of curvature of the distal end 144 of the tip assembly 140.

[0091]FIG. 14 is a side elevational view of the distal end of a finishedcatheter 100 prior to shaping with any one of the jigs described withrespect to FIGS. 5-10 below. According to one embodiment of the presentinvention, the tip assembly 140 may be formed from several differentsections that are bonded together and to the shaft 110. The formation ofthe tip assembly in sections permits greater control of the diameter andstiffness of various sections. As illustrated in FIG. 14, these sectionsmay include a proximal section 1420 that is bonded to the flexible shaft110, an intermediate section 1480 which may be shaped to bendapproximately ninety degrees relative to the shaft 110 and which isbonded to the proximal section 1420, and a distal section 1440 that isbonded to the intermediate section 1480 and which includes a pluralityof electrodes and a distal end tip or cap electrode 147.

[0092]FIG. 15 is a cross sectional view of the distal end tip assembly140 of FIG. 14 taken along line 15-15 in FIG. 14. According to oneembodiment of the present invention, the tip assembly 140 comprises atubular proximal section 1420 and a tubular distal section 1440 alignedcoaxially with the shaft 110. Between the proximal section 1420 and thedistal section 1440 is an intermediate section 1480 that may be shapedto bend approximately ninety degrees relative to the shaft 110. Asillustrated, in one embodiment, the proximal section 1420 may be ofapproximately the same outer diameter as the shaft 110, and the distalsection 144 and the intermediate section 1480 can also be ofapproximately the same outer diameter, but a slightly smaller diameterthan the proximal section 1420 and the shaft 110. In other embodiments,the various sections forming the tip assembly 140 may be of the sameouter diameter as the shaft 110.

[0093] In the illustrated embodiment, the distal section 1440 of the tipassembly 140 terminates in a distal end or cap electrode 147 which isalso coaxially aligned with the shaft 110 and sections 1420, 1440, and1480. A threaded collar 1520 is secured to the distal end of distalsection 1440 to retain the electrode cap 147. It should be appreciatedthat other embodiments need not include the threaded collar 1520 and thedistal end or cap electrode 147, and may for example, instead utilize anon-conductive cap.

[0094] Shaft 110 may include a single lumen 1525 which extends thelength of the shaft 110 from the distal end of the handle 120. Thesingle-lumen 1525 may be used to house the pull cables 1128 a-d and theelectrode wires 1510. Each pull cable and each electrode wire preferablyincludes a sheath.

[0095] The electrical portion of the tip assembly 140 may include aplurality spaced ring-type electrodes 146 along with a distal end or capelectrode 147. The electrodes provide signal information on heartpotentials to the remote recording device 160 (FIG. 1) used by theelectrophysiologist. The ring-type electrodes 146 and the cap electrode147 are electrically connected to respective signal wires 1510. Thesignal wires 1510 are routed through the length of the core 1120 througha central lumen 1125 in each of the proximal 1420, intermediate 1480,and distal 1440 sections, as illustrated in FIGS. 15, 16, and 17 andattached to a respective electrode 146, 147. The signal wires 1510 arepreferably electrically insulated from each other and therefore may allshare a single lumen as shown. The signal wires 1510 extend proximallythrough the handle 120 to the connector 130 which enables the electrodes146 and 147 to be easily coupled electrically to the recording device160. In the illustrated embodiment, the two pull cables 1110 a and 1110b that extend nearly the length of the tip assembly 140 are used tocontrol the radius of curvature of the distal section 1440. The othertwo pull cables 1110 c and 11110 d are used to control bending of thetip assembly 140 in a plane that is perpendicular to the longitudinalaxis (L) of the shaft 110 (See FIG. 14). As shown in FIGS. 15, 16, and17, the pull cables 1110 c and 1110 d terminate proximally of theintermediate section 1480. In one embodiment, each of the pull cables1110 c and 11110 d terminates in a ball 1530 which may be made from anysuitable material, and which is larger in diameter than the lumens 1128c and 1128 d in which the pull cables are housed. For example, each ofthe pull cables 1110 c and 1110 d may be passed through a hole in theball (not shown) and the end tied to prevent the cable from comingloose. Other methods of terminating the cables 1110 c and 1110 d aredescribed in the aforementioned patents, for example, by tying the endsof the cables 128 c and 1128 d together at a distal end of proximalsection 1420.

[0096] It should be appreciated that an additional pair of pull cablesmay also be provided to control bending of the tip assembly 140 in aplane that is perpendicular to the longitudinal axis of the shaft 110and perpendicular to the other plane of motion provided by pull cables1110 c and 1110 d. Thus, depending upon the number of pull cables andthe number of actuators disposed on the handle 120, the radius ofcurvature of the distal end of the tip assembly 140 may be increased ordecreased, and the orientation of the tip assembly 140 may be changed intwo different directions in each of two orthogonal planes (e.g., a Yplane and a Z plane) that are perpendicular to the longitudinal axis ofthe shaft.

[0097] The proximal section 1420 includes a central lumen 1125 forpassing all of the electrode wires 1510 to the intermediate 1480 anddistal 1440 sections, and for passing two of the pull cables 110 a and110 b. The proximal section 1440 also includes two proximal cable lumens1128 c and 1128 d which pass pull cables 1110 c and 1110 d from thelumen 1525 in the shaft 110 through the length of the proximal section1420. Proximal cable lumens 1128 c and 1128 d may contain respectivestiffening wires 1710 (FIG. 17) to reduce axial twisting of proximalsection 1420. The proximal section 1420 includes a reduced diameterproximal end so that the proximal section 144 may be mated to the distalend of the shaft, within the distal end of the shaft 110.

[0098] The intermediate section 1480 is thermally bonded to the distalend of the proximal section 1420 and the proximal end of the distalsection 1440. The intermediate section 1480 includes two reduceddiameter ends so that it may snugly nest inside the proximal and distalsections. The intermediate section 1480 includes two cable lumens 1128 aand 1128 b and a central lumen 1125. Additional lumens may also beincluded, as described further below. Pull cables 1110 a and 1110 b fromthe central proximal section lumen 1125 are routed to the outwardlydisposed cable lumens 1128 a and 1128 b, respectively, at a point justpast the distal end of the central lumen 1125 of the proximal section1420. A small transition space is provided between the lumens of theintermediate and proximal sections to permit the pull cables 1110 a,1110 b to be radially displaced.

[0099] The distal section 1440 is thermally bonded to the distal end ofthe intermediate section 1480 and has approximately the same outerdiameter as the intermediate section 1480. The distal end of theintermediate section 1480 is recessed within the distal section 1440 toprovide a smooth transition between the two sections. The distal section1440 also includes two cable lumens 1128 a and 1128 b and a centrallumen 1125. The distal section 1440 may also include additional lumens(shown in FIG. 16), that may be used, for example, to house a controlwire for a sliding electrode, to house an irrigation line, to house awire for a localization sensor, etc. The ends of the pull cables 1110 aand 1110 b emanating from the outwardly disposed cable lumens 1128 a and1128 b, respectively, may be tied together and/or potted with an epoxy.The electrode wires 1510 from the central lumen 1125 are fed throughradial apertures in the core 1120 and soldered or welded (or bonded witha conductive epoxy) onto an undersurface of the ring electrodes 146, asillustrated in FIGS. 15A and 16. The wire for the distal end or capelectrode may be fed through the central lumen 1125 and soldered,welded, or epoxied onto the cap electrode 147.

[0100] In the embodiment illustrated in FIG. 15, each of the pluralityof ring electrodes 146 are recessed within the outer circumferentialsurface of the distal section to provide a low profile. However, forcertain procedures, such as ablation, it may be preferable to have theouter surface of one or more of the electrodes 1546 protrude above theouter circumferential surface of the distal section, such as illustratedin FIG. 1 SA, and illustrated in phantom in FIG. 16. It should beappreciated that a variety of different types of electrodes may be usedwith the tip assembly depicted in FIG. 15, as the present invention isnot limited to any particular type, or construction of electrode.

[0101] Various configurations can be used to locate and anchor the pullcables within the shaft and the proximal, intermediate and distalsections of the tip assembly. In general, it is preferable to conductthe pull cables as close as possible to the outer circumference of thesection controlled by the cables in order to increase the bendingmoment. For this reason, the controlling cables for both the proximaland distal sections are directed to outer lumens, i.e., lumens 1128 cand 1128 d and lumens 1128 a, 1128 b. However, prior to reaching thesection that is controlled by the cables, the cables are preferablycentrally routed, for example in central lumen 1125, so thatmanipulation of cables controlling movement of more distal sections ofthe catheter do not affect the orientation of more proximal sections ofthe catheter. The illustrated construction has been found to be anoptimal arrangement from the points of view of manufacturing ease andfunction. Other arrangements, however, can also be used. For example,the pull cables can be conducted through the proximal, intermediate, anddistal sections exclusively through outer lumens. Examples of otherarrangements for the pull cables within the tip assembly 140 aredescribed in the aforementioned U.S. Pat. Nos. 5,383,852, 5,462,527, and5,611,777.

[0102] Active Bend

[0103] As noted above, the approximately ninety degree bend in thedistal end tip assembly 140 may be either fixed (e.g., permanentlyformed with the use of ajig, such as jigs 500, 700, and 900, describedin detail with respect to FIGS. 5-10 below), or active (e.g., movablebetween approximately zero and approximately ninety degrees relative tothe longitudinal axis of the shaft 110 of the catheter 100) through theuse of an actuator 122, 124 disposed on the handle 120. FIGS. 21 and 21Aillustrate an embodiment of the present invention that includes such an“active bend.”

[0104] As shown in FIG. 21, in one embodiment, the distal end tipassembly 140 includes a proximal section 2120, an intermediate section2180 that may be actively bent via manipulation of a control cable (FIG.21A) attached to an actuator (e.g., actuator 122) on the control handle120 to be approximately perpendicular to the longitudinal axis of theshaft 110, and a distal section 2140 having a radius of curvature thatcan be adjusted via manipulation of a control cable attached to anactuator (e.g., actuator 124) on the handle 120. The distal section 2140includes one or more electrodes 146, 147 disposed along a length of thedistal section 2140.

[0105] As shown in FIG. 21A, which is a cross section of the proximalsection 2120 of the tip assembly 140 taken along line 21A-21A in FIG.21, the cables 1110 c and 1110 d that control bending of theintermediate section 2180 may be formed from a single cable that iswrapped around a reduced diameter end of the proximal section 2120 andthat is recessed within the intermediate section 2128 in a mannersimilar to that described with respect to FIG. 12 in U.S. Pat. No.5,383,852. In general, the cable will be wrapped about that portion ofthe tip assembly that is immediately prior to the point at which bendingis to occur. In this embodiment, tension applied to cable 1110 c resultsa bending of the distal section 2140 of the tip assembly 140 in adownward direction (as seen in FIG. 21) to orient the arcuately curveddistal section 2140 in a plane that is perpendicular to the longitudinalaxis of the shaft 110, and tension applied to cable 1110 d results inthe bending of the distal section 2140 of the tip assembly 140 in anupward direction (as seen in FIG. 21) to return to its position alongthe longitudinal axis of the shaft. Because the handle 120 may berotated one hundred and eighty degrees, the ability to bend the distalsection in an opposite direction is unnecessary, but may be provided, ifdesired. It should be appreciated that in other embodiments, only asingle control wire may be used.

[0106] To accommodate such an active curve, the material from which theintermediate section 2180 is formed should be less stiff than thematerial from which the shaft 110 is formed so that bending occurs inthe intermediate section 2180. Preferably, the material from which thedistal section is formed is less stiff than that from which theintermediate section is formed to permit the radius of curvature of thedistal section 2140 to be changed without altering the orientation ofthe intermediate and proximal sections 2180 and 2120, respectively.

[0107] To facilitate bending in a known and controlled manner, theintermediate section 2180 is preferably permanently biased to have abend of a few degrees relative to the longitudinal axis (L) of the shaft110. Because the intermediate section 2180 is permanently biased a fewdegrees away from the longitudinal axis (L) of the shaft 110, tensionapplied to cable 1110 c, for example, results in bending of theintermediate section 2180 in the plane of the bend toward a ninetydegree angle with the longitudinal axis (L) of the shaft 110. Tensionapplied to the opposing cable, for example 1110 d, results in bending ofthe intermediate section 2180 in the plane of the bend back toward thelongitudinal axis (L) of the shaft 110. Because the intermediate section2180 is biased a few degrees away from the longitudinal axis (L) of theshaft 110 in a particular direction, any bending of the intermediatesection 2180 occurs in the plane aligned in the same direction as thatbend in a known and controlled manner. Were the intermediate section2180 not biased in a particular direction, bending could occur in anydirection.

[0108] Electrode Configurations

[0109] As noted above, embodiments of the present invention are notlimited to a particular construction, type, or number of electrodesdisposed along the distal end of the tip assembly. For example,embodiments of the present invention may include a plurality oflow-profile ring type electrodes 146 disposed along the distal end ofthe tip assembly 140, such as shown in FIG. 2, with or without a distalend or cap electrode 147. Alternatively, a plurality of raised profilering type electrodes may be used, such as the electrode 1546 illustratedin FIG. 15A, with or without a distal end or cap electrode 147.Alternatively still, a combination of raised and low profile electrodesmay be used.

[0110] Where multiple mapping electrodes are used, pairs of mappingelectrodes 146 (FIG. 2) may be used to determine a location of lowestconductivity on the septal wall, or a preferred location to puncture theseptal wall during a transeptal procedure. Each of the mappingelectrodes 146 may detect a voltage signal, which is transmitted tocontroller 150 via cable 115 (FIG. 1). Voltage may be measuredinstantaneously or continuously by each of the electrodes 146.Continuous voltage measurements generate an electrogram (a voltagesignal that changes with time) for each electrode. The voltage detectedby each electrode may be determined with respect to a referenceelectrode, termed a unipolar voltage measurement, or may be determinedwith respect to another electrode of a pair, termed a bipolar voltagemeasurement. Thus, a pair of mapping electrodes may generate twounipolar electrograms, each with respect to a reference electrodelocated elsewhere on the catheter 100, or a single bipolar electrogramrepresenting the voltage between each pair of electrodes. As unipolarand bipolar voltage measurement are well understood by those skilled inthe art, further discussion is omitted herein.

[0111] It should be appreciated that the electrodes may be constructedfrom a variety of materials, including non ferromagnetic materials suchas gold, platinum, and silver, or they may be constructed from aconductive epoxy. The electrodes may be individual electrodes, or may becontinuous electrodes, similar in construction to a coiled springwrapped about the distal end of the tip assembly. The electrodes may befixed in position along the distal end of the tip assembly, oralternatively, may be movable along a length of the distal end of thetip assembly. An example of such a movable electrode is now describedwith respect to FIG. 18.

[0112] As shown in FIG. 18, the distal end 144 of the tip assembly 140may include a movable electrode 1846 that is movable between a firstposition and a second position spaced apart along a length of the distalend 144 of the tip assembly 140. In the embodiment illustrated, themovable electrode 1846 slides along a length of the distal end 144 thanspans approximately 360 degrees, and when used for ablation, may be usedto form a circular lesion. The very distal end of the tip assembly mayinclude a cap electrode 1847, or alternatively, the cap may be made froma non-conductive material and may simply serve to terminate the verydistal end of the tip assembly. Where a cap electrode 1847 is used, aninsulating spacer may be placed proximally of the cap electrode toprevent the movable electrode 1846 from electrically contacting the capelectrode 1847.

[0113] As shown in FIG. 19, which is a cross sectional side view of thedistal end of the tip assembly in FIG. 18 taken along line 19-19, theelectrode 1846 may be attached to a cylindrically-shaped plastic slider1910 that that can slide back and forth along a length of the distal end144 of the tip assembly. In the embodiment shown, the distal end of ametal push/pull wire 1920 is welded to an outer surface of the electrode1846, with the proximal end of the push/pull 1920 wire being attached toan actuator 122, 124 on the handle 120. The push/pull wire 1920 may bedisposed within the central lumen 1125 from the handle 120 to theintermediate section 1480 of the tip assembly 140 (FIG. 15), wherein itthen passes through one of the outer lumens 1110 c, 1110 d of the distalsection. The distal end of the push/pull wire 1920 emanates through aslit 1930 in the core 1120. It should be appreciated that in embodimentswhere it is desired that the push/pull wire 1920 not be electricallyconnected to the electrode, the push/pull wire 1920 may be attached tothe plastic slider 1910, rather than to the electrode 1846. It shouldalso be appreciated that the push/pull wire 1920 need not be made frommetal, as non-conducting materials may also be used, as known to thoseskilled in the art.

[0114]FIG. 20 is a cross sectional end view of distal end of the tipassembly illustrated in FIG. 19, taken along line 20-20. FIG. 20illustrates the slit 1930 in the core 1120 through which the push/pullwire 1920 protrudes, with the remaining elements having already beendescribed. Further details of the sliding electrode described withrespect to FIGS. 18-20 are provided in commonly assigned U.S. Pat. No.6,245,066, which is hereby incorporated by reference in its entirety.

[0115] The Handle

[0116] A handle assembly in accordance with one embodiment of theinvention, is shown in FIGS. 22-33. The handle configuration shown inthese drawings uses rotational movement of the thumbwheel actuator 122to selectively control the tension applied to the pull cables 1110 c and1110 d which control the orientation of the tip assembly 140 relative tothe longitudinal axis of the shaft 110, and linear movement of the slideactuator 124 to selectively control the tension applied to pull cables1110 a and 1110 b that control the radius of curvature of the distal end144 of the tip assembly 140.

[0117] Referring to FIG. 22, the handle 120 comprises a housing having aleft section 2200L and a right section 2200R. These two sections 2200Land 2200R are somewhat semicircular in cross section and have flatconnecting surfaces which may be secured to each other along a commonplane to form a complete housing for the handle 120. The outer surfacesof the handle 120 are contoured to be comfortably held by the user.

[0118] A wheel cavity 2210 is formed within the right section 2200R ofthe handle 120. The wheel cavity 2210 includes a planar rear surface2211 which is generally parallel to the flat connecting surface of thehandle 120. The thumb wheel actuator 122 is a generally circular dischaving a central bore 2216, an integrally formed pulley 2218, and upperand lower cable anchors 2220. Upper and lower cable guides 2221 serve toretain the cables 1110 c and 1110 d within a guide slot or groove 2223formed in a surface of the integrally formed pulley 2218. In theembodiment illustrated, the thumbwheel 122 rotates about a sleeve 2228inserted in the central bore 2216. The thumbwheel 122 is held inposition by a shoulder nut 2224 that mates with a threaded insert 2229in the planar rear surface 2211 of the right section 2200R of the handle120. To provide friction that permits the thumbwheel to maintain itsposition even when tension is applied to one of the cables 1110 c, 1110d, a friction disk 2226 is provided between the shoulder nut 2224 andthe thumbwheel 122. Tightening of the shoulder nut 2224 increases theamount of friction applied to the thumbwheel 122.

[0119] A peripheral edge surface 2222 of the thumb wheel 122 protrudesfrom a wheel access opening so that the thumb wheel 122 may be rotatedby the thumb of the operator's hand which is used to grip the handle120. To ensure a positive grip between the thumb wheel 122 and theuser's thumb, the peripheral edge surface 2222 of the thumb wheel 122 ispreferably serrated, or otherwise roughened. Different serrations onopposite halves of thumb wheel 122 enable the user to “feel” theposition of the thumb wheel.

[0120] The left section 2200L supports part of the mechanism forselectively tensioning each of the two pull cables 1110 a and 110 b thatcontrol the radius of curvature of the distal end 144 of the tipassembly 140. To accommodate the protruding portion of the thumb wheel122, the left handle section 2200L includes a wheel access openingsimilar in shape to the wheel access opening of the right handle section2200R. It also includes an elongated slot 2230 in its side surface.

[0121] A slider 2232 is provided with a neck portion 2242 which fitssnugly within the slot 2230. The slider 2232 includes a forward cableanchor 2235 and a rear cable anchor 2236 for anchoring the pull cables1110 a and 1110 b. Pull cable 1110 b is directly attached to the forwardcable anchor 2235 and becomes taught when the slider 2232 is movedtoward the distal end of the handle 120. Pull cable 1110 a is guided bya return pulley 2238 prior to being attached to the rear cable anchor2236 and becomes taught when the slider 2232 is moved toward theproximal end of the handle 120. The return pulley 2238 is rotatablyattached to a pulley axle 2239 which is supported in a bore (not shown)in the flat surface of the right handle section 2200R. The return pulley2238 may include a groove (not shown) to guide pull cable 1110 a. In theillustrated embodiment, a cable guide 2205 is attached to the righthandle section 2200R to guide the cables 1110 a-1110 d and prevent theirentanglement with one another. As shown, cables 110 a and 1110 b arerouted up and over the cable guide 2205, while cables 1110 c and 1110 dare routed through a gap 2206 in the cable guide 2205. Grooves may beformed in a top surface of the cable guide 2205 to keep cables 1110 aand 1110 b in position, although they could alternatively be routedthrough holes formed in the cable guide 2205, or by other suitablemeans.

[0122] A slider grip 2252 is attached to the neck portion 2242 of theslider 2232 and positioned externally of the handle 120. The slider grip2252 is preferably ergonomically shaped to be comfortably controlled bythe user. Together, the slider 2232 and the slider grip 2252 form theslide actuator 124 depicted in FIG. 1. Preload pads 2254 are positionedbetween the outer surface of the left handle section 2200L and theslider grip 2252 (shown in FIGS. 22 and 25). By tightening the screws2260 that attach the slider grip 2252 to the slider 2232, friction isapplied to the slider 2232 and thus, to the pull cables 1110 a, 1110 b.Preload pads 2237 may also be placed on a surface of the slider 2232 fora similar purpose.

[0123] A dust seal 2234 (FIGS. 22 and 26) having an elongated slit andpreferably made from latex is bonded along the slot 2230 within the lefthandle section 2200L. The neck portion 2242 of the slider 2232 protrudesthrough the slit of the dust seal 2234 so that the slit only separatesadjacent to the neck portion 2242. Otherwise, the slit remains “closed”and functions as an effective barrier preventing dust, hair and othercontaminants from entering the handle 120. Further details of the handle122 are described in U.S. Pat. Nos. 5,383,852, 5,462,527, and 5,611,777.

[0124] According to a further aspect of the present invention, each ofthe thumbwheel actuator and the slide actuator may include means forimparting a first amount of friction on at least one pull cable to whichthe actuator is attached when the actuator is in a first position, andfor imparting a second and greater amount of friction on the at leastone pull cable when the actuator is moved away from the first position.According to this aspect of the present invention, the first positionmay correspond to a neutral position of the actuator wherein the tipassembly is aligned with the longitudinal axis of the shaft, or aneutral position of the actuator wherein the radius of curvature of thedistal end of the tip assembly is neither being actively reduced orincreased, and the second position may correspond to a position of theactuator that is other than the neutral or rest position.

[0125] As should be appreciated by those skilled in the art, it isdesirable that the actuators for changing the orientation of the tipassembly and for controlling the radius of curvature of the distal endof the tip assembly remain in a fixed position, once actuated.Conventionally, this has been achieved by providing a sufficient amountof friction between the actuator and another surface on the handle 122to resist movement of the actuator unless a certain amount of force isapplied to the actuator. For example, in FIG. 22, by tightening shouldernut 2224 that holds the thumbwheel in position, a greater amount offorce must be applied to the thumbwheel to rotate the thumbwheel fromone rotational position to another. Similarly, and with respect to theslide actuator 124, by tightening the two screws 2260 that hold theslider grip 2252 in position against an undersurface of the handlesection, a greater amount of force must be applied to the slide actuator124 to move the slide actuator 122 from one position to another.

[0126] Although this conventional approach is straightforward, itresults in the same amount of friction being applied to the actuator(s)in all positions, and not merely those positions that deviate from aneutral or rest position. Thus, in use, it can be difficult to ascertainwhether the orientation of the tip assembly or the radius of curvatureof the distal end of the tip assembly is in a neutral state, withoutvisually looking at the handle. This can be problematic, as the user ofthe catheter would need to divert his or her attention to visuallyinspect the position of the actuator(s). Further, Applicants havedetermined that the frictional force imparted by the mechanisms thatmaintain the cables and actuators in a fixed position can significantlydecrease over time, for example, while stacked on the shelf, oftentimesrequiring that the mechanisms used to impart such friction (e.g., theshoulder nut and the screws) be tightened prior to use. It is believedthat this phenomena is due to material creep associated with the variousmaterials used to form the actuator mechanisms. This decrease infrictional force is especially apparent where the catheter has beenbrought to elevated temperatures during a sterilization cycle, as thematerials from which the handle and the control mechanisms are formedhave a tendency to yield at elevated temperatures. Although the variousmechanisms may be tightened after sterilization, such tightening maycontaminate the sterile nature of the catheter, and is undesirable in aclinical setting.

[0127] According to a further aspect of the present invention, each ofthe thumbwheel actuator and the slide actuator may include means forimparting a first amount of friction on at least one pull cable to whichthe actuator is attached when the actuator is in a first position, andfor imparting a second and greater amount of friction on the at leastone pull cable when the actuator is moved away from the first position.This difference in the frictional force can be perceived by the user toalert the user as to when the actuator is in a neutral or rest position,without visually inspecting the actuator. Further, because thefrictional forces on the actuating mechanisms are reduced in a neutralor rest position, the catheter may be sterilized with the actuator(s) ina neutral or rest position, thereby reducing yielding of the actuationmechanism during sterilization.

[0128] According to one embodiment that is directed to the thumbwheelactuator, the means for imparting different amounts of friction mayinclude a plurality of detents formed in the planar rear surface of thehandle housing that cooperate with corresponding plurality of detents ina lower surface of the thumbwheel. In this embodiment, each of theplurality of detents in the lower surface of the thumbwheel receives aball or bearing that sits partially within the respective detent. In afirst neutral position, each of the balls also rest within a respectivedetent in the rear surface of the handle and exert a first amount offriction on the thumbwheel and the pull cables attached thereto. But, asthe thumbwheel is rotated, the balls ride outside the detent in the rearsurface of the handle onto the elevated surface above, thereby exertinga second and greater amount of friction on the thumbwheel and the pullcables attached thereto. According to one embodiment, this second amountof friction is sufficient to prevent the thurnbwheel from returning toits neutral position. FIGS. 22, 26, 27, and 28 illustrate oneimplementation of a means for imparting different amounts of frictionfor a thumbwheel actuator 122 according to this embodiment of thepresent invention.

[0129] As shown in FIGS. 22, 26, 27, and 28, the planar rear surface2210 of the right section 2200R includes a plurality of detents 2212formed therein. A corresponding number of detents 2215 are provided inan undersurface of the thumbwheel 122 (FIGS. 26-28). Within each of theplurality of detents 2215 in the undersurface of the thumbwheel is aball or bearing 2214. The balls or bearing may be made from any suitablematerial, such as stainless steel, or may alternatively be made from ahard plastic. The balls or bearings 2214 may be fixed in position forexample, with an epoxy, or permitted to rotate within the detents 2215.It should be appreciated that the balls or bearings 2214 mayalternatively be seated within the detents 2212 in the planar rearsurface 2211 of the right section of the handle 2200R. In a neutral orrest position, for example, corresponding to an orientation of the tipassembly that is parallel to the longitudinal axis of the shaft, each ofthe plurality of balls rests within a corresponding detent 2212 in theplanar rear surface 2211. Such a resting or neutral state is depicted inFIG. 27 which is a schematic cross sectional view of the thumbwheel ofFIG. 22. As may be appreciated, this neutral or rest positioncorresponds to a position of reduced friction on the thumbwheel 122 inwhich the friction disk 2226 is compressed to only a small degree, andthus, to a reduced frictional force on the pull cables that are attachedto the thumbwheel.

[0130] As the thumbwheel 122 is rotated from this neutral or restposition, the balls 2214 ride up and out of their respective detents2212 and along the path 2265 indicated in FIG. 22. In this secondposition wherein each of the balls contacts the elevated planar rearsurface 2211, a second and greater amount of friction is imparted to thethumbwheel, and thus, the pull cables attached thereto, that tends toprevent the thumbwheel from moving to another position without furtherrotational force applied to the thumbwheel. FIG. 28 is a schematic crosssectional view of the thumbwheel of FIG. 22 illustrating a state inwhich the thumbwheel is in a position other than the neutral or restposition. As can be seen in FIG. 28, each of the balls 2214 rests uponthe elevated planar rear surface 2211 and the friction disk 2226 iscompressed relative to that shown in FIG. 27. As shown best in FIG. 22,each of the detents 2212 in the planar rear surface 2211 may includelead in/lead out sections 2267 that are gradually tapered to the levelof the planar rear surface 2211 to facilitate smooth movement of theballs 2214 out of and into the detents 2212.

[0131] Although the present invention is not limited to the number ofdetents 2212, 2215 incorporated into the handle and the thumbwheel,Applicants have found that three detents spaced equally about acircumference of the planar rear surface 2211 and the thumbwheel 122distributes stress evenly about the thumbwheel 122 and permits asufficient amount of rotation before another detent 2212 is encountered.Furthermore, although the present invention is not limited to the amountof force applied to the thumbwheel to change the position of thethumbwheel, Applicants have empirically determined that a force ofapproximately 4 to 8 pounds is sufficient to resist any forces on thepull cables. Moreover, this amount of force is sufficient so that thethumbwheel cannot be moved inadvertently, and does not require greatstrength by the user. This amount of force also accounts for anyyielding during storage and/or sterilization.

[0132] Although this embodiment of the present invention has beendescribed in terms of a plurality of detents in a surface of the handleand a corresponding number of detents that hold a ball or bearing in anundersurface of the thumbwheel, the present invention is not so limited.For example, and as discussed above, the detents in the planar surface2211 of the handle 120 may hold the balls or bearings 2214 and not thethumbwheel. Moreover, it should be appreciated that other means ofimparting different frictional forces on the thumbwheel may be readilyenvisioned. For example, rather than detents, the rear planar surface2211 may be contoured to include a plurality of ramps (for example,three ramps). The undersurface of the thumbwheel 122 may include acorresponding plurality of complementary shaped ramps such that when thethumbwheel 122 is in a neutral or rest position, a minimum of frictionis imparted, and as the thumbwheel 122 is rotated, the heightenedsurface of the ramps on the undersurface of the thumbwheel 122 contactsa heightened surface of the ramps in the planar surface. As thethumbwheel 122 is rotated further, addition friction is imparted.

[0133] According to another embodiment that is directed to the slideactuator, the means for imparting different amounts of friction mayinclude a ramp disposed on or formed within the handle 120. In thisembodiment, the apex of the ramp corresponds to a neutral position ofthe slide actuator 122. In this neutral position, a minimum amount offriction is applied to the slider 2232 and the pull cables 1110 a, 1110b attached thereto. As the slider 2232 is moved forward or backward awayfrom the neutral position, the slider 2232 is pushed toward thethumbwheel and an interior surface of the housing to impart a greatamount of friction on the slider and the pull cables attached thereto.As with the thumbwheel, this second amount of friction is sufficient toprevent the slider from returning to its neutral position.

[0134]FIGS. 23, 24, and 26 illustrate one implementation of a means forimparting different amounts of friction for a slide actuator 124. Asshown in these Figures, the undersurface of the left section 2200Lincludes a ramp 2610. The ramp may be integrally formed within the leftsection 2200L of the handle 120, or alternatively, the ramp 2610 may beseparate from the handle and attached thereto. As illustrated in FIG. 26which is a schematic cross sectional view of the slide actuator 124shown in FIGS. 1 and 22, the ramp 2610 includes a central section ofdecreased thickness and proximal and distal sections that increase inthickness away from the central section until flush with theundersurface of the left section. The top surface of the slider 2232that contacts the undersurface of the left section 2200L of the handlemay have a complementary shape to the ramp as shown in FIGS. 23 and 24.In the position shown in FIG. 23, the slide actuator is in a neutral orrest position corresponding to a first radius of curvature of the distalend of the tip assembly. The two screws 2260 force the slider grip 2252and the slider 2232 closer to one another and compress the preload pads2254 therebetween. In the neutral or rest position shown in FIGS. 23 and25, the preload pads 2254 are compressed to only a minimal extent.However, as the slider 2232 is moved away from the neutral or restingposition, the shape of the ramp 2610 (and the slider 2332) imparts anadditional frictional force that tends to separate the slider 2232 fromthe slider grip 2252, thereby compressing the preload pads 2254 to agreater extent, as illustrated in FIG. 24. This additional frictionalforce resists the slide actuator 124 from changing position, absentfurther force on the slide actuator 124.

[0135] Although this embodiment of the present invention has beendescribed in terms of a ramp formed within or disposed on anundersurface of the handle 122, the present invention is not so limited.For example, the ramp may alternatively be formed on an outer surface ofthe handle and provide similar functionality. Other means for impartingdifferent frictional forces on the slide actuator may be readilyenvisioned by those skilled in the art.

[0136] Although the above described embodiments for imparting a varyingamount of friction on at least one pull cable have been described withrespect to a catheter in which the diameter of curvature of the distalend, or the orientation of the distal end of the tip assembly, can bechanged by manipulation of an actuator attached to the pull cable, thepresent invention is not so limited. For example, the means forimparting a varying amount of friction may also be used with a push/pullcable and a movable electrode described above. Alternatively, the meansfor imparting a varying amount of friction may be used to impart varyingamounts of friction to a cable that is used to deploy a braidedconductive member in the manner described in co-pending and commonlyassigned U.S. patent application Ser. No. 09/845,022, entitled APPARATUSAND METHODS FOR MAPPING AND ABLATION IN ELECTROPHYSIOLOGY PROCEDURES,filed Apr. 27, 2001, and incorporated herein by reference. Accordingly,it should be appreciated that this embodiment of the present inventionmay be used to impart varying amounts of friction on any cable thatcontrols movement of one portion of the catheter with respect toanother.

[0137]FIG. 29A illustrates another handle that may be used withembodiments of the present invention. In the embodiment depicted in FIG.29A, the handle 120 includes three actuators 122, 124, and 124 a forcontrolling movement of the tip assembly 140. For example, thethumbwheel actuator 122 may be used to change the orientation of the tipassembly 140 relative to the longitudinal axis of the shaft 110 of thecatheter 100 in one or two different directions depending on the numberof cables attached thereto. The first slide actuator 124 may be used toincrease and/or decrease the radius of curvature of the distal end 144of the tip assembly 140. The second slide actuator 124 a may be used tocontrol the orientation of the of the tip assembly 140 relative to thelongitudinal axis of the shaft 110 of the catheter 100 in one or twodifferent direction of movement that are orthogonal to the directionsprovided by use of the thumbwheel actuator 122. Alternatively, thesecond slide actuator 124A may be used to move a sliding electrode (SeeFIG. 18) proximally and distally along the distal end of the tipassembly. Alternatively still, the thumbwheel actuator 122 or the firstslide actuator 124 may be used for changing the orientation of the tipassembly or the radius of curvature of the distal end in a firstdirection, and the second slide actuator 124 a may be used for changingthe orientation of the tip assembly or the radius of curvature in theopposite direction. Alternatively still, the first slide actuator 124may be used for controlling an active bend (see FIG. 21), the thumbwheelactuator 122 may be used for changing the radius of curvature of thedistal end of the tip assembly, and the second slide actuator 124 a maybe used for changing the orientation of the tip assembly in a firstand/or second direction (e.g., for steering of the proximal end of thetip assembly.) FIG. 29B illustrates another handle that includes a thirdactuator. In the embodiment illustrated in FIG. 29B, the third actuatoris a plunger-type actuator 126 that is conventionally used for a varietyof different purposes in the medical industry. In the illustratedembodiment, the plunger-type actuator may be used to move a slidingelectrode proximally and distally along the distal end of the tipassembly, with the thumbwheel 122 and slide 124 actuators being used forsteering of the proximal end of the tip assembly and changing the radiusof curvature of the distal end of the tip assembly, respectively, orvice versa. Although the use of a handle having up to three differentactuators has been described, it should be appreciated that more thanthree different actuators may be provided. For example, a thumbwheelactuator, two slide actuators, and a plunger-type actuator may be usedto control an active bend, a sliding electrode, changing the radius ofcurvature of the distal end, and steering of the proximal end of the tipassembly.

[0138]FIGS. 30-32 illustrate a control handle for a catheter accordingto another embodiment of the present invention. As illustrated in FIG.31, a surface of the handle 120 may include a plurality of ribs ordetents 3010 to provide tactile feedback to a user. For example, as theslider grip 2252 is moved proximally and distally on the handle, thismovement can be felt by the user. Such feedback permits the user tounderstand that the radius of curvature of the distal end of the tipassembly, or the orientation of the tip assembly has been changed,without requiring the user to visually perceive the movement of theslider grip 2252. In the embodiment illustrated in FIG. 31, theplurality of ribs are formed integrally with the handle 120 and disposedon an outer surface thereof. To prevent the preload pads 2254 fromcatching on the ribs or detents 3010, a hard thin layer of material suchas plastic may be applied to the surface of the preload pads thatcontact the outer surface of the handle 120. In the embodiment shown,the leading and trailing edges of the pads 2254 are also curved awayfrom the outer surface of the handle 120 to avoid rough movement.

[0139]FIG. 32 illustrates an alternative embodiment of the handle 120that includes a plurality of ribs or detents 3010 that are formedintegrally with the handle 120 and disposed on an inner surface of thehandle 120. As the preload pads 2252 do not directly contact the ribs ordetents 3010, a hard layer such as that described above with respect to

[0140]FIG. 31 is not necessary. With each of the embodiments describedabove, it should be appreciated that the ribs or detents 3010 should belarge enough to provide tactile feedback to the user, but not so largeas to be disturbing to the user, or to result in rough and abruptmovement of the slide actuator 124 when moved from one position toanother. Applicants have empirically determined that a protrusion of theribs or detents 3010 approximately 1 mm above, or below the surface ofthe handle meets these objectives. Although the use of ribs or detentshas been described with respect to providing feedback to a user onmovement of the distal end of the catheter, the present invention is notso limited. For example, the ribs or detents may be used to providefeedback relating to movement of a movable electrode, or a braidedconductive mesh.

[0141] Accordingly, the use of tactile features for providing feedbackto a user may be used wherever it is useful to provide feedback to auser on the movement of one portion of the catheter with respect toanother.

[0142] According to another embodiment of the present invention, ahandle for use with a catheter having an elongated shaft and a tipassembly is provided. According to this embodiment, the handle mayinclude graphical indicia indicative of a radius of curvature of adistal end of the tip assembly. This embodiment is now described withrespect to FIG. 33.

[0143] As shown in FIG. 33, the handle 120 of the catheter 100 caninclude graphical indicia 3310 that identifies the radius of curvatureof the distal end of the tip assembly.

[0144] In the embodiment shown, the graphical indicia 3310 are disposedon the handle 120 adjacent to the slide actuator 124, which in thisembodiment controls the radius of curvature of the distal end of the tipassembly. As illustrated, the graphical indicia 3310 identify thediameter of curvature in centimeters, with a position of two centimeterscorresponding to a neutral position of the slide actuator. Movement ofthe slide actuator 124 distally on the handle 120 increases the radiusof curvature of the distal end of the tip assembly, and movement of theslider 124 proximally on the handle 120 decreases the radius ofcurvature. Although not illustrated in FIG. 33, the graphical indicia3310 may also identify the number of circles formed by the distal end ofthe tip assembly. For example, a first numeric indicator can precedeeach of the illustrated numeric indicators to identify the number ofcircles formed by the distal end of the tip assembly. For example, anindicator of 2.1 can indicate two complete circles of the distal end ofthe tip assembly with a diameter of 1 cm, with an indicator of 1.2indicating one complete circle of the distal end of the tip assemblywith a diameter of 2 cm. Alternatively, the number of circles formed bythe distal end of the tip assembly may be placed on the other side ofthe slide actuator 124. Other representations of both the diameter ofcurvature and the number of circles formed by the distal end of the tipassembly may be readily envisioned. It should be appreciated that thegraphical indicia permit a user to roughly determine the diameter of anendocardial or epicardial site without recourse to otherinstrumentation, other than the catheter itself.

[0145] Although the provision of graphical indicia has been describedwith respect to the slide actuator 124, it should be appreciated that asimilar provision may be made for the thumbwheel actuator 122. Ingeneral, although the provision of graphical indicia may associated withthe thumbwheel 122 may not be very useful when related to theorientation of the tip assembly, the operation of the thumbwheel 122 andthe slide actuator 124 may be reversed, such that the thumbwheel 122 isused to control the radius of curvature of the distal end of the tipassembly, and the slide actuator 124 is used to control the orientationof the tip assembly. Where the thumbwheel 122 is used to control theradius of curvature of the distal end of the tip assembly, graphicalindicia 3010 may be provided on the thumbwheel at different rotationalpositions (e.g., at zero degrees, at thirty degrees, as sixty degrees,etc. to serve a similar purpose.

[0146] Although the provision of graphical indicia has been describedwith respect to providing feedback to a user on the radius of curvatureof the distal end of the catheter, it should be appreciated that otheruses may be readily envisioned. For example, the use of graphicalindicia may be used to identify the state of deployment of a braidedmesh that is disposed at the distal end of the catheter, or to identifythe location of a movable electrode that is disposed on the distal endof the catheter.

[0147] Temperature Sensing and Localization

[0148] Temperature sensing refers to a number of techniques whereby thetemperature in the vicinity surrounding distal end 144 of the tipassembly 140 may be measured. Measuring temperature is important,particularly during ablation procedures, so as to avoid overheating orcharring tissue. The catheter of the present invention can provide formeasuring the temperature of the distal end 144 of the tip assembly 140and the mapping electrodes disposed thereon at the same time. Thetemperature of the distal end 144 can then be used to provide feedbackfor control of ablation energy generator 170 and the temperature of themapping electrodes can be monitored to be certain that the tissue thatis being ablated is in fact being destroyed or rendered non-electricallyconductive.

[0149] In a further embodiment of the invention, one or more of theplurality of ring or band-type electrodes 146 may be replaced with aring or band-shaped temperature sensor. Reference is now made to FIG.34, which illustrates a ring-shaped ablation electrode 146 and aring-shaped temperature sensor 3410. Temperature sensor 3410 may be athermocouple, thermistor, or any other device for sensing temperature.The temperature sensor 3410 detects the heat of the tissue duringablation by ring or band-shaped ablation electrode 146. Temperaturesensing is important during ablation because overheated tissue mayexplode or char, releasing debris into the bloodstream. Ablationelectrode 146 is connected to connector 130 (FIG. 1) via wire 3420,which in turn connects to ablation energy generator 170; ring-shapedtemperature sensor 3410 is connected to connector 130 via wire 3430,which in turn connects to controller 150. Ring-shaped electrode 146 canserve as both a reference electrode and an ablation electrode, and maybe switched between applications by the controller 150 or by a humanoperator.

[0150] A temperature sensor or sensors, such as, but not limited to oneor more thermocouples may be attached to the catheter 100 fortemperature sensing during ablation procedures. The temperature sensormay be in contact with the heart tissue or, alternately, may not be incontact with the heart tissue. In other embodiments, temperature sensorsmay be disposed within one or more of the mapping electrodes 146, 147,for example in a hole drilled within the electrode. One skilled in theart will appreciate that more than one temperature sensor may be used inany particular configuration of catheter 100.

[0151] Localization refers to a number of techniques whereby thelocation of catheter 100 in a patient can be determined. Apparatus andmethods for localization can be incorporated into catheter 100.

[0152] Referring again to FIG. 34, the distal end 144 of the tipassembly 140 may include an electromagnetic sensor 3450 that may be usedfor localization. Electromagnetic sensor 3450, may be fixed within thetip assembly 140 of the catheter 100 using any suitable mechanism, suchas glue or solder. The electromagnetic sensor 3450 generates signalsindicative of the location of the electromagnetic sensor. A wire 3440electrically connects the electromagnetic sensor 3450 to the controller150, allowing the generated signals to be transmitted to the controller150 for processing.

[0153] In addition to the electromagnetic sensor 3450 fixed in thedistal end of the tip assembly 140, a second electromagnetic sensor (notshown) may be provided that is fixed relative to the patient. The secondelectromagnetic sensor is attached, for example, to the patient's body,and serves as a reference sensor. A magnetic field is also provided,which is exposed to the electromagnetic sensors. Coils within eachelectromagnetic sensor generate electrical currents when exposed to themagnetic field. The electrical current generated by the coils of eachsensor corresponds to a position of each sensor within the magneticfield. Signals generated by the reference electromagnetic sensor andelectromagnetic sensor 3450 fixed to the catheter are analyzed by thecontroller 150 to ascertain a precise location of electromagnetic sensor3450.

[0154] Further, the signals can be used to generate a contour map of theheart. The map may be generated by contacting the distal end 144 of thetip assembly 140 with the heart tissue at a number of locations alongthe heart wall. At each location, the electric signals generated by theelectromagnetic sensors are transmitted to the controller 150, or toanother processor, to determine and record a location of the distal endof the tip assembly. The contour map is generated by compiling thelocation information for each point of contact. This map may becorrelated with heart signal data, measured by one or more electrodes onthe distal end of the tip assembly, for each location to generate a mapof both the shape and electrical activity of the heart. Signalsgenerated by the electromagnetic sensors may also be analyzed todetermine a displacement of the distal end of the tip assembly caused byheartbeat.

[0155] As an alternative to the use of electromagnetic sensors otherconventional techniques, such as ultrasound or magnetic resonanceimaging (MRI) can also be used for localization of tip assembly.Moreover, an impedance-based sensor can also be incorporated into thetip assembly. In an impedance-based system, several, such as three, highfrequency signals are generated along different axes. The catheterelectrodes may be used to sense these frequencies, and with appropriatefiltering, the strength of the signal and thus the position of thecatheter can be determined.

[0156] One skilled in the art will appreciate that the construction ofcatheter 100 may be optimized to make use of the various localizationtechniques.

[0157] Methods for Making the Tip Assembly

[0158]FIGS. 5-10 illustrate a number of different jigs that may be usedto form a tip assembly having a fixed bend of approximately ninetydegrees followed by an arcuately curved distal end. Each of these jigsmay be used with a finished catheter (i.e., a catheter which is alreadyfully assembled, and including a handle 120 and electrodes 146, 147disposed on the distal end of the tip assembly 140), a partiallyfinished tip assembly (i.e., a tip assembly 140 that includes electrodes146, 147, that is not yet attached to shaft 110 and the handle 120 (FIG.1)), or an unfinished tip assembly 140 (i.e., a tip assembly 140 withoutany electrodes 146, 147).

[0159]FIGS. 5 and 6 illustrate a first jig 500 that is formed from ahollow tube. In one embodiment, the hollow tube is formed fromhypodermic stainless steel tubing, although other materials, such as ahigh temperature plastics such as TEFLON, DELRIN, etc., mayalternatively be used. The material from which the jig 500 is formedshould be thermally stable, such that its shape does not change whensubjected to temperature in the range of 200-400 degrees Fahrenheit. Inone embodiment, the tube used to form the jig 500 has an outer diameterof approximately 0.83 inches and an inner diameter of approximately 0.72inches to accommodate a tip assembly 140 that is approximately 6 Frenchin diameter, although these dimensions may be varied to accommodatedifferent diameter tip assemblies. For example, to accommodate a tipassembly that is 10 French in diameter, a larger diameter tube would beused. As shown in FIG. 5, the distal end of the jig 500 is formed in acircle having an inner diameter of approximately 0.44 inches and anouter diameter of approximately 0.61 inches. Although the presentinvention is not limited to any particular dimensions, these dimensionsmay be used to form a tip assembly 140 in which the diameter ofcurvature of the distal end 144 in a resting state is approximately 20mm. Further, and as described in more detail below, these dimensions areselected to account for a certain amount of rebounding (approximatelyfifteen to twenty percent) in the tip assembly 140 after removal fromthe jig. Although embodiments of the present invention are not limitedto a tip assembly having a diameter of curvature of approximately 20 mmin a resting state, this size advantageously permits the catheter to beused for mapping and/or ablation procedures within a blood vessel, suchas a pulmonary vein. It should be appreciated that for other endocardialor epicardial sites, other dimensions may be used.

[0160] As shown in FIG. 6, the jig 500 has a first straight region 510,followed by a curved region 520 having an approximately ninety degreebend relative to the straight region 510, and terminates in an arcuatelyshaped curved region 530 defining approximately a circle (i.e., spanningapproximately 360 degrees). In one embodiment, the straight region 510is approximately 0.125 inches in length, and the curved region 520 hasan inner radius 515 of approximately 0.2 inches. It should beappreciated that other dimensions may be used to impart a differentshape to the tip assembly, and to accommodate tip assemblies having adifferent outer diameters (e.g., a 10 French diameter tip assembly).

[0161] According to one embodiment of the present invention, the tipassembly 140 is inserted into the straight region 510 of the jig 500 andthe distal end 144 of the tip assembly 140 is advanced until the verydistal end of the tip assembly 140 is adjacent the distal end of the jig500. The jig 500 and the tip assembly 140 are then heated at apredetermined temperature for a predetermined time to permanently shapethe tip assembly 140. Applicants have found that heating the jig 500 andthe tip assembly 140 at a temperature of approximately 200 to 400degrees Fahrenheit for approximately thirty minutes to an hour issufficient to permanently shape the tip assembly 140 to the desiredshape. It should be appreciated that the lower the temperature, thegreater amount of time is needed to permanently shape the tip assembly140, and that the time and temperature to which the tip assembly 140 andthe jig 500 are heated may vary dependent upon the materials used toform the tip assembly 140 and the jig 500. It should further beappreciated that because catheters may be sterilized prior to use orafter use, the temperature to which the tip assembly 140 and the jig 500is heated should be approximately 20 degrees Fahrenheit above thetemperature at which the catheter is sterilized. This helps to preventthe tip assembly 140 from returning to its original shape duringsterilization. During sterilization, a retainer may be used to hold thetip assembly 140 in the desired shape.

[0162] After heating the tip assembly 140 and the jig 500 for thepredetermined time at the predetermined temperature, the tip assembly140 and the jig 500 are allowed to cool, and the tip assembly 140 isremoved from the jig 500. After removal, Applicants have found thearcuately curved distal end 144 of the tip assembly 140 tends to reboundby approximately fifteen to twenty percent, but that further reboundingat temperatures similar to those of human body temperature does notoccur. Further, by modifying the materials from which the tip assembly140 is formed, and by controlling the temperature and the time at whichthe tip assembly 140 is shaped, rebounding to less than three percent isexpected. It should be appreciated that because a certain amount ofrebounding is to be expected, the dimensions of the jig 500 should besized to accommodate the expected amount of rebounding.

[0163] The jig of FIGS. 5 and 6 may be used to impart a desired shape tothe tip assembly 140 of a finished catheter or to a partially finishedtip assembly. For example, in the described embodiment, the length ofthe straight region 510 is relatively short to permit the tip assembly140 of a finished catheter to be inserted into the jig 500 withoutdamaging the electrodes 146, 147. This can be advantageous in amanufacturing setting, as finished catheters can be shaped as desiredafter construction and testing, and prior to shipment to an end user.This may allow fewer distinct catheters to be stocked by themanufacturer of the catheter. Alternatively, in a hospital setting, theability to shape a finished catheter can allow fewer catheters to bestocked at the hospital, with each of the catheters being capable ofbeing shaped as desired, prior to use.

[0164] For use with partially finished tip assemblies, the length of thestraight region 510 may be lengthened, with any excess material beingcut to length as desired. Moreover, with partially finished tipassemblies, the distal end of the jig 500 may form more than onecomplete circle, or may form a helical shape. Although the jig 500depicted in FIGS. 5 and 6 was used to receive a tip assembly, it shouldbe appreciated that a solid wire of a similar shape may alternatively beused. For example, the hollow stock from which the tip assembly isformed may be fed onto a solid wire having the desired shape, and thenheated at an elevated temperature to produce the desired shape. Theformed stock can then be removed from the wire, cut to the desiredlength, and finished in a conventional manner.

[0165]FIGS. 7 and 8 illustrate a second jig that may also be used toform a tip assembly having the desired shape. In particular, the jig ofFIGS. 7 and 8 may be used to permanently shape the distal end of acatheter so that it includes an approximately ninety degree bendfollowed by an arcuately curved section. According to this embodiment,the jig 700 includes a cylindrical mandrel 740 and a cylindricalretainer 750. The cylindrical mandrel 740 and the cylindrical retainer750 may be formed from any suitable high temperature materials, such asstainless steel, aluminum, anodized aluminum, or high temperatureplastics. In one embodiment, the mandrel 740 has an outer diameter ofapproximately 0.75 inches and is approximately 2.5 inches long, and theretainer 750 has an inner diameter that is slightly greater than theouter diameter of the mandrel 740, so that the mandrel 740 can be fitwithin. Although the present invention is not limited to thesedimensions, the above-identified dimensions may be used to shape thedistal end tip assembly of a catheter so that it is uniquely suited foruse inside a blood vessel; such as a pulmonary vein, and to accommodatean anticipated amount of rebounding after removal of the distal end tipassembly from the jig. It should be appreciated that for applicationsrelating to other endocardial sites, other dimensions may be suitablyemployed.

[0166] As shown in FIGS. 7 and 8, the mandrel 740 has a passageway toreceive a tip assembly 140 that includes a first straight region 710, acurved region 720 having an approximately ninety degree bend relative tothe straight region 710, and an arcuately shaped curved region 730defining a circle. The passageway may be formed in a conventionalmanner, for example with a milling machine. In one embodiment, thestraight region 710 is approximately 1.9 inches in length, and thecurved region 720 has an inner radius 715 of approximately 0.2 inches;the depth of the passageway is approximately 0.068 inches and the widthis approximately the same. The described dimensions are selected toshape a tip assembly that is well suited for use within a blood vesselsuch as a pulmonary vein, although it should be appreciated that otherdimensions may be suitably employed for use with different anatomicalstructures and for different applications. Again, the dimensions of themandrel 740 and the retainer 750 should be selected to accommodate theexpected amount of rebounding. In the embodiment shown, the arcuatelyshaped curved region 730 is spaced apart from the end of the mandrel 740to facilitate insertion of the mandrel 740 into the retainer 750.

[0167] According to one embodiment of the present invention, a tipassembly 140 is placed into the passageway, and the mandrel 740 and thetip assembly 140 are inserted into the retainer 750. The retainer 750acts to hold the tip assembly 140 in place within the passageway of themandrel 740. The jig 700 and the tip assembly 140 are then heated at apredetermined temperature for a predetermined time to permanently shapethe tip assembly 140 in a manner similar to that described above withrespect to the first jig 500. Because of the larger thermal mass of thejig 700 relative to the jig 500, Applicants have found that a longertime may be needed to shape the tip assembly 140 than with the first jig500, for example, about 20 additional minutes. To lessen the amount oftime required to shape the tip assembly 140, the mandrel 740 may behollowed out, for example. After heating the tip assembly 140 and thejig 700 for the predetermined time at the predetermined temperature, thetip assembly 140 and the jig 700 are allowed to cool, and then the tipassembly 140 is removed from the jig 700. As with the jig of FIGS. 5 and6, the jig 700 may be used to impart a desired shape to the tip assembly140 of a finished catheter or to a partially finished tip assembly.Indeed, because the tip assembly 140 is placed within the passagewayrather than being threaded through it, the jig 700 is particularly wellsuited for use with a finished tip assembly, as damage to the finishedtip assembly resulting from contact with the jig can be avoided.

[0168]FIGS. 9 and 10 illustrate another jig that may be used to form atip assembly 140 having an approximately ninety degree bend followed byan arcuately curved distal end. According to this embodiment, the jig900 includes a disk-shaped mandrel 940 and a circular cover 950. Thedisk-shaped mandrel 940 and the circular cover 950 may again be formedfrom any suitable high temperature materials, such as stainless steel,aluminum, anodized aluminum, or high temperature plastics. The cover 950is removably attached to the mandrel 940 by a fastener 960, such as athreaded screw, that is passed through an aperture 980 in the cover 950.The mandrel 940 may include a threaded aperture to receive the fastener960. Attached to the mandrel 940 is a tubular extension 970 that may bemade from any suitable material, and which is attached, for example,with a high temperature epoxy or by welding to the mandrel. The tubularextension 970 may be used to support the proximal end 142 of the tipassembly 140 without substantially increasing the thermal mass of thejig 900.

[0169] As shown in FIGS. 9 and 10, the mandrel 940 has a passageway toreceive a tip assembly 140 that includes a first straight region 910, acurved region 920 having an approximately ninety degree bend relative tothe straight region 910, and an arcuately shaped curved region 930defining a circle. The arcuately shaped curved region 930 may be formedby milling an annular groove in a top surface of the mandrel 940, whilethe straight region 910 may be formed by drilling a through hole througha section of arcuately shaped curved region 930, for example. A ninetydegree bend is formed at the intersection of the annular groove and thethrough hole. In one embodiment, the arcuately shaped curved region 930has an outer diameter of approximately 0.5 inches and the annular groovehas a width of approximately 0.07 inches. The above-described dimensionsare selected to shape the tip assembly so that it is well suited for usewithin a blood vessel such as a pulmonary vein, although it should beappreciated that other dimensions may be suitably employed for use withdifferent anatomical structures and for different applications. Thedepth of the groove should be sufficiently greater than the outerdiameter of the tip assembly 140 so that the bend in the tip assembly140 takes place over a length of the tip assembly 140. For example, inone embodiment, the depth of the groove is approximately twice the widthof the groove to avoid an immediate ninety degree bend in the tipassembly 140. Such an immediate bend could interfere with operation ofthe control cables that are used to adjust the radius of curvature ofthe distal end 144 of the tip assembly 140. Again, the dimensions of themandrel 940 should be selected to accommodate the expected amount ofrebounding, and the desired dimensions and shape of the tip assembly140.

[0170] According to one embodiment of the present invention, a tipassembly 140 is threaded through the tubular extension 970 and thestraight region 910 of the mandrel 940, and the distal end 144 of thetip assembly 140 is placed into the annular groove in the mandrel 940.The cover 950 is then fastened to the mandrel 940. The cover 950 acts tohold the tip assembly 140 in place within the passageway of the mandrel940. The jig 900 and the tip assembly 140 are then heated at apredetermined temperature for a predetermined time to permanently shapethe tip assembly 140 in a manner similar to that described above withrespect to the first and second jigs. After heating the tip assembly 140and the jig 900 for the predetermined time at the predeterminedtemperature, the tip assembly 140 and the jig 900 are allowed to cool,and then the tip assembly 140 is removed from the jig 900.

[0171] As with the previously described jigs 500 and 700, the jig 900may be used to impart a desired shape to the tip assembly 140 of afinished catheter or to a partially finished tip assembly. Because thedistal end of the tip assembly is inserted straight ahead into themandrel 940, rather than along a curved path, the jig 900 is alsoparticularly well suited for use with a finished tip assembly, as damageto the finished tip assembly resulting from contact with the jig can beavoided.

[0172] Although the jigs 500, 700, and 900 of FIGS. 5-10 have beenillustrated and described as being useful in forming a tip assemblyhaving a fixed bend of approximately ninety degrees followed by anarcuately curved distal end, it should be appreciated that each of thesejigs may also be used or modified for use with a tip assembly includingan active bend, such as described above with respect to FIG. 19. Forexample, for creating a permanent bias of a few degrees relative to thestraight regions 510, 710, and 910, the approximately ninety degree bendmay have a larger radius that may be varied according to the intendeduse of the tip assembly. As noted above with respect to FIG. 19, bypermanently biasing the intermediate section 2180 (FIG. 19) away fromthe straight regions 510, 710, and 910, bending takes place in a knownand controlled manner. Moreover, it should be appreciated that ratherthan terminating in a curved region 530, 730, 930 that spansapproximately 360 degrees in a single plane (e.g., a circle), the curvedregion 530, 730, and 930 may be formed in a helical shape.

[0173] Methods of Use

[0174] As discussed above, the catheter system of the invention may beused in mapping and/or ablation applications. In one embodiment of theinvention, the mapping or ablation is performed in the heart of apatient. In the mapping application, multiple signals may be receivedfrom the heart tissue via multiple electrodes on the catheter. Eachelectrode may measure a continuous signal (i.e., electrogram) from theheart tissue. The continuous signal may represent the voltage of theheart tissue in contact with the electrode, with respect to a referencevoltage, as it changes with time. The reference voltage may be obtainedusing a dedicated reference electrode or another measurement electrode.The quality of the signal received by each electrode improves as boththe size of the electrode and the isolation of the electrode increases.

[0175] Preferably, multiple electrodes are employed, such that multipleelectrograms may be obtained simultaneously. This allows for multipledata points, which can result in a more precise mapping of the heartsignal and a shorter required measurement time. A shorter measurementtime advantageously reduces the x-ray exposure to patients andphysicians during fluoroscopy, when employed during the catheterprocedure.

[0176] The mapping function of the catheter can be used for a number ofdifferent applications. For example, in one application, the cathetermay be used to measure the conductivity at various points of the septalwall, which separates the left and right sides of the heart, todetermine a preferred sight for puncture of the septal wall. In anotherapplication, the conductivity of the heart tissue may be measuredbetween adjacent electrodes in contact with the heart tissue todetermine the continuity of a lesion formed by ablation. In stillanother application, the catheter may used to identify electricalsignals within the heart that are characteristic of a number of heartconditions. For example, the focus site of an arrhythmia (e.g., atrialfibrillation, AV nodal tachycardia or tachycardia resulting fromWolff-Parkinson-White syndrome).

[0177] Reference is now made to FIG. 35, which illustrates a method ofinsertion of the catheter 100 into a patient 3510 in accordance with anembodiment of the present invention. The catheter 100 is inserted intothe patient via a blood vessel, e.g., subclavian vein, jugular vein, orfemoral vein. In FIG. 35, the catheter 100 is shown entering a femoralvein 3520 via an incision 3530 in the thigh of the patient 3510. Thecatheter 100 may be introduced into the vein using a sheath/dilator (notshown). The sheath/dilator may be anchored at the incision site, forexample by stitching the sheath/dilator to the patient's skin at thearea of incision 3530. From the incision site 3530 in the femoral vein3520, the catheter 100 may be advanced independently, or through asheath/dilator, up the inferior vena cava 3540 into the right atrium ofthe heart.

[0178] Reference is now made to FIG. 36, which illustrates a diagram ofa cross-sectional view of the heart taken along line A-A in FIG. 35. Thecatheter 100 is shown entering the right atrium 3610 via the inferiorvena cava 3540. For passage of the catheter 100 into the left atrium,3620 the distal end of the catheter 100 may be passed trans-septallythrough the septal wall 3630. In one method, a puncture 3640 in theseptal wall 3630 is made at the foramen ovale, an area of the septalwall having a decreased thickness and decreased conductivity relative toother areas of the septal wall. As described previously, electrodes onthe distal end of the catheter 100 may be used to locate the foramenovale, or another preferred site to puncture the septal wall 3630. Asshown in FIG. 36, the distal end of the tip assembly 140 of the catheter100 traverses the septal wall 3630 from the right atrium 3610 and entersthe left atrium 3620. The distal end of the catheter 100 may be used formapping and/or ablation procedures in the left atrium 3620 or may bemaneuvered into the pulmonary vein(s) for mapping and/or ablation. Itshould be appreciated that the catheter may also be used to performmapping and/or ablation in the right heart, in the ventricles, or in anyother area of the heart or blood vessels of the circulatory system, andthat the catheter 1 need not pass through the septal wall to enter theseareas.

[0179] Referring now to FIG. 37, which is an expanded view of FIG. 36,in one embodiment of the present invention, once inside the left atrium3620, the distal end of the catheter 100 may be advanced towards theostium of one of the pulmonary veins 3710. In this embodiment, theradius of curvature of the distal end 144 of the tip assembly 140 isremotely adjusted to snugly fit against the annular walls of thepulmonary vein 3710 by manipulation of the actuator 122, 124 (FIG. 1)that controls the radius of curvature of the distal end 144 of the tipassembly 140. In this position, the graphical indicia 3310 (FIG. 33) onthe handle 120 may be used to give the user an indication of thediameter of the ostium of the pulmonary vein at this location. Mappingmay be performed, as can ablation.

[0180] Because of the approximately ninety degree bend in the tipassembly 140, pressure applied to the handle 120 is translated via theshaft to force the arcuately curved distal end 144 of the tip assembly140 tightly against the ostium of the pulmonary vein 3710. In thisposition, the user may also apply pressure to the actuator (e.g., theslide actuator 124) that controls the radius of curvature of the distalend 144 of the tip assembly 140 to also apply an outwardly radialpressure that further forces the distal end 144 of the tip assembly 140tight against the ostium of the pulmonary vein 3710. Mapping may then beperformed to locate a focal trigger or triggers of atrial fibrillation.It should be appreciated that the ability to force the distal end 144 ofthe tip assembly 140 tightly against the inner circumferential surfaceof a blood vessel, such as the ostium of a pulmonary vein, enhances theability to accurately locate a focal trigger or triggers of atrialfibrillation.

[0181] Should ablation be determined to be an effective solution,ablation energy may then be provided by the ablation energy generator170 (FIG. 1) to create a circular lesion around the circumference of theostium of the pulmonary vein 3710. By controlling which electrodes(disposed on the distal end of the tip assembly, but not shown) are usedto provide such ablation energy, a full circumferential lesion or apartial circumferential lesion may be created. Further, by monitoring ofthe temperature of at the site (for example, by using one or moretemperature sensors disposed along the distal end 144 of the tipassembly 140), care may be exercised to ensure that charring isprevented and that the appropriate temperatures necessary for ablationare achieved. After ablation, the mapping electrodes may then be used toverify that the electrical conductivity of the tissue has beendestroyed.

[0182] One advantage of using a catheter according to the invention inthe described method is that only a single catheter is necessary to (1)determine the location of the foramen ovale for passage through theseptal wall, (2) perform any desired mapping procedures, and (3) performany desired ablation procedures. This avoids the need for changingcatheters during procedures as between, for example, mapping andablation procedures. It may also reduce the number of removal andreinsertion operations needed during a patient's electrophysiology studyand treatment procedure. Further, because the radius of curvature of thedistal end of the tip assembly may be remotely altered within theendocardial site, the catheter may be used on any sized patient from aninfant or small animal to an adult or large animal, as “one size fitsall.” Moreover, should the size of a blood vessel or other anatomicalstructure be different than that which was anticipated, it is notnecessary to remove the catheter and insert another more appropriatelysized catheter. As noted above, this ability to be used with any sizedpatient can also reduce the need for a manufacturer or a care providerto stock a number of differently sized catheters.

[0183] The various configurations of the catheter illustrated in thefigures are exemplary. One skilled in the art will appreciate that thenumber, size, orientation, and configuration of the mapping electrodesand the ablation electrodes, as well as various diameters and lengths ofthe catheter can be provided depending upon the particular application.

[0184] Having thus described at least one illustrative embodiment of theinvention, various alterations, modifications, and improvements willreadily occur to those skilled in the art. Such alterations,modifications, and improvements are intended to be within the spirit andscope of the invention. Accordingly, the foregoing description is by wayof example only and is not intended as limiting. The invention islimited only as defined in the following claims and the equivalentsthereto.

What is claimed is:
 1. An electrophysiology catheter comprising: ahandle having a distal end and a proximal end, the handle including anactuator; a flexible shaft having a proximal end and a distal end and alongitudinal axis that extends along a length of the shaft, the proximalend of the shaft being attached to the distal end of the handle; a tipassembly having a proximal end and a distal end, the proximal end of thetip assembly being attached to the distal end of the shaft and thedistal end of the tip assembly being biased in an arcuately curved shapehaving a radius of curvature; and a cable, attached to the actuator andthe distal end of the tip assembly, that extends through the shaft, thecable being adapted to change the radius of curvature of the distal endof the tip assembly in response to movement of the actuator.
 2. Thecatheter of claim 1, wherein the proximal end of the tip assemblyincludes a fixed bend of approximately ninety degrees relative to thelongitudinal axis of the shaft, and wherein the arcuately curved shapeof the distal end of the tip assembly is oriented in a plane that isapproximately perpendicular to the longitudinal axis of the shaft. 3.The catheter of any of claims 1-2, wherein the cable is adapted toreduce the radius of curvature of the distal end of the tip assembly inresponse to movement of the actuator in a first direction.
 4. Thecatheter of claim 3, wherein the distal end of the tip assembly curvesat least three hundred and sixty degrees in response to movement of theactuator in the first direction.
 5. The catheter of claim 3, wherein thedistal end of the tip assembly curves at least five hundred and fortydegrees in response to movement of the actuator in the first direction.6. The catheter of any of claims 1-2, wherein the cable is adapted toincrease the radius of curvature of the distal end of the tip assemblyin response to movement of the actuator in a first direction.
 7. Thecatheter of any of claims 1-2, wherein the cable is a first cable thatis adapted to reduce the radius of curvature of the distal end of thetip assembly in response to movement of the actuator in a firstdirection, the catheter further comprising: a second cable, attached tothe actuator and the distal end of the tip assembly, that extendsthrough the shaft, the second cable being adapted to increase the radiusof curvature of the distal end of the tip assembly in response tomovement of the actuator in a second direction that is opposite to thefirst direction.
 8. The catheter of claim 7, wherein the radius ofcurvature of the distal end of the tip assembly can be varied betweenapproximately 1.5 mm and 25 mm in response to movement of the actuator.9. The catheter of claim 7, wherein the radius of curvature of thedistal end of the tip assembly can be varied between approximately 5 mmand 17.5 mm in response to movement of the actuator.
 10. The catheter ofany of claims 7-9, wherein the radius of curvature of the distal end ofthe tip assembly in a resting state corresponding to a neutral positionof the actuator is approximately 9 mm.
 11. The catheter of any of claims7-10, wherein the actuator is a first actuator, wherein the handlefurther includes a second actuator, disposed on the handle, the catheterfurther comprising: a third cable, attached to the second actuator andthe proximal end of the tip assembly, that extends through the shaft,the third cable being adapted to bend the proximal end of the tipassembly in a third direction that is perpendicular to the longitudinalaxis of the shaft.
 12. The catheter of claim 11, further comprising: afourth cable, attached to the second actuator and the proximal end ofthe tip assembly, that extends through the shaft, the fourth cable beingadapted to bend the proximal end of the tip assembly in a fourthdirection that is perpendicular to the longitudinal axis of the shaft.13. The catheter of claim 12, wherein the fourth direction is oppositeto the third direction and wherein the handle further includes a thirdactuator, disposed on the handle, the catheter further comprising: afifth cable, attached to the third actuator and the proximal end of thetip assembly, that extends through the shaft, the fifth cable beingadapted to bend the proximal end of the tip assembly in a fifthdirection that is perpendicular to the longitudinal axis of the shaftand perpendicular to the third and fourth directions.
 14. The catheterof claim 12, wherein the distal end of the tip assembly includes amovable electrode and wherein the handle further includes a thirdactuator, disposed on the handle, the catheter further comprising: afifth cable, attached to the third actuator and the movable electrode,that extends through the shaft, the fifth cable being adapted to changea position of the movable electrode along the arcuately curved shape ofthe distal end of the tip assembly.
 15. The catheter of any of claims1-5, wherein the actuator is a first actuator, wherein the handlefurther includes a second actuator, disposed on the handle, the catheterfurther comprising: a second cable, attached to the second actuator andthe proximal end of the tip assembly, that extends through the shaft,the second cable being adapted to bend the proximal end of the tipassembly in a first direction that is perpendicular to the longitudinalaxis of the shaft.
 16. The catheter of claim 15, further comprising: athird cable, attached to the second actuator and the proximal end of thetip assembly, that extends through the shaft, the third cable beingadapted to bend the proximal end of the tip assembly in a seconddirection that is perpendicular to the longitudinal axis of the shaft.17. The catheter of claim 16, wherein the first direction is opposite tothe second direction.
 18. The catheter of claim 16, wherein the firstdirection is perpendicular to the second direction.
 19. The catheter ofany of claims 1-5, wherein the cable is formed from a non-ferromagneticmaterial.
 20. The catheter of any of claims 1-5, wherein the actuator isa first actuator, wherein the cable is a first cable, wherein the distalend of the tip assembly includes a movable electrode, and wherein thehandle further includes a second actuator disposed on the handle, thecatheter further comprising: a second cable, attached to the secondactuator and the movable electrode, that extends through the shaft, thesecond cable being adapted to change a position of the movable electrodealong the arcuately curved shape of the distal end of the tip assembly.21. The catheter of claim 1, wherein the proximal end of the tipassembly includes a fixed bend of a few degrees relative to thelongitudinal axis of the shaft, wherein the actuator is a firstactuator, wherein the cable is a first cable, and wherein the handlefurther includes a second actuator, disposed on the handle, the catheterfurther comprising: a second cable, attached to the second actuator andthe proximal end of the tip assembly, that extends through the shaft,the second cable being adapted to bend the distal end of the tipassembly so that the arcuately curved shape of the distal end of the tipassembly is oriented in a plane that is approximately perpendicular tothe longitudinal axis of the shaft in response to movement of the secondactuator.
 22. The catheter of claim 21, wherein the first cable isadapted to reduce the radius of curvature of the distal end of the tipassembly in response to movement of the first actuator in a firstdirection, the catheter further comprising: a third cable, attached tothe first actuator and the distal end of the tip assembly, that extendsthrough the shaft, the third cable being adapted to increase the radiusof curvature of the distal end of the tip assembly in response tomovement of the first actuator in a second direction that is opposite tothe first direction.
 23. The catheter of claim 22, wherein the radius ofcurvature of the distal end of the tip assembly can be varied betweenapproximately 1.5 mm and 25 mm in response to movement of the firstactuator.
 24. The catheter of claim 22, wherein the radius of curvatureof the distal end of the tip assembly can be varied betweenapproximately 5 mm and 17.5 mm in response to movement of the firstactuator.
 25. The catheter of any of claims 22-24, wherein the radius ofcurvature of the distal end of the tip assembly in a resting statecorresponding to a neutral position of the first actuator isapproximately 9 mm.
 26. The catheter of any of claims 22-25, wherein thehandle further includes a third actuator, disposed on the handle, thecatheter further comprising: a fourth cable, attached to the thirdactuator and the proximal end of the tip assembly, that extends throughthe shaft, the fourth cable being adapted to bend the proximal end ofthe tip assembly in a third direction that is perpendicular to thelongitudinal axis of the shaft.
 27. The catheter of claim 26, furthercomprising: a fifth cable, attached to the third actuator and theproximal end of the tip assembly, that extends through the shaft, thefifth cable being adapted to bend the proximal end of the tip assemblyin a fourth direction that is perpendicular to the longitudinal axis ofthe shaft and opposite to the third direction.
 28. The catheter of anyof claims 22-25, wherein the distal end of the tip assembly includes amovable electrode and wherein the handle further includes a thirdactuator, disposed on the handle, the catheter further comprising: afourth cable, attached to the third actuator and the movable electrode,that extends through the shaft, the fourth cable being adapted to changea position of the movable electrode along the arcuately curved shape ofthe distal end of the tip assembly.
 29. The catheter of any of claims1-13 and 15-27, wherein the distal end of the tip assembly includes amapping electrode.
 30. The catheter of claim 29, wherein the mappingelectrode is movable along the arcuate curve of the distal end of thetip assembly.
 31. The catheter of any of claims 29-30, wherein themapping electrode is made from a non-ferromagnetic material.
 32. Thecatheter of claim 29, wherein the distal end of the tip assembly furtherincludes an ablation electrode.
 33. The catheter of any of claims 1-13and 15-27, wherein the distal end of the tip assembly includes anelectrode that can be used for both mapping and ablation.
 34. Thecatheter of claim 33, wherein the electrode is movable along thearcuately curved shape of the distal end of the tip assembly.
 35. Thecatheter of any of claims 1-13 and 15-27, wherein the distal end of thetip assembly includes a plurality of mapping electrodes disposed alongthe arcuatetly curved shape of the distal end of the tip assembly. 36.The catheter of claim 35, wherein the plurality of mapping electrodesproject above a circumferential surface of the distal end of the tipassembly.
 37. The catheter of any of claims 35-36, wherein the pluralityof mapping electrodes includes a tip electrode disposed at a tip of thedistal end of the tip assembly.
 37. The catheter of any of claims 35-37,wherein at least one of the plurality of mapping electrodes can also beused for ablation.
 38. The catheter of any of claims 1-37, wherein thedistal end of the tip assembly includes a position sensor disposed inthe distal end of the tip assembly.
 39. The catheter of any of claims1-38, wherein the distal end of the tip assembly further includes atemperature sensor disposed on the distal end of the tip assembly. 40.The catheter of any of claims 1-5, wherein the cable is a pull cable.41. The catheter of any of claims 1-5, wherein the actuator is movablebetween a first position corresponding to a first radius of curvature ofthe distal end of the tip assembly and a second position correspondingto a second radius of curvature of the distal end of the tip assemblythat is different than the first radius of curvature of the distal endof the tip assembly, wherein the handle includes: frictional means forimparting a first amount of friction on the actuator when the actuatoris in the first position and for imparting a second amount of frictionon the actuator when the actuator is moved away from the first position,the second amount of friction being greater than the first amount offriction.
 42. The catheter of claim 41, wherein the handle furtherincludes: graphical indicia, disposed on the handle adjacent theactuator, indicative of the radius of curvature of the distal end of thetip assembly in the first position and in the second position.
 43. Thecatheter of claim 41, wherein the handle further includes: graphicalindicia, disposed on the handle adjacent the actuator, indicative of theradius of curvature of the distal end of the tip assembly in the firstposition.
 44. The catheter of any of claims 41-43, wherein the handlefurther includes: a plurality of protrusions, disposed on at least oneof the handle and the actuator, to provide tactile feedback to a userwhen the actuator is moved from the first position.
 45. The catheter ofany of claims 41-44, wherein the handle is formed from a housing thatincludes a first section and a second section, wherein the actuatorincludes a thumbwheel that is positioned between the first and secondsections, the thumbwheel having a central bore about which thethumbwheel rotates, wherein the frictional means includes: a frictiondisk having a central bore spaced adjacent to the thumbwheel; a shouldernut that is received within the central bores of the friction disk andthe thumbwheel and that attaches the friction disk and the thumbwheel tothe first section; and a plurality of complimentary mating featuresdisposed on a flat surface of the thumbwheel and on a flat surface ofone of the first and second sections, that force the thumbwheel intotighter engagement with the friction disk when the thumbwheel is movedaway from the first position.
 46. The catheter of claim 45, wherein theflat surface of the thumbwheel and the flat surface of the one of thefirst and second sections each includes a plurality of radially spaceddetents, and wherein the plurality of complimentary mating featuresinclude: a corresponding plurality of bearings secured within one of theflat surface of the thumbwheel and the one of the first and secondsections.
 47. The catheter of claim 46, wherein each of the plurality ofdetents in the other of the flat surface of the thumbwheel and the oneof the first and second sections is shaped to allow the bearings tosmoothly exit the detents when the thumbwheel is moved away from thefirst position.
 48. The catheter of any of claims 41-44, wherein thehandle is formed from a housing that includes a first section and asecond section, the first section including a slit, wherein the actuatoris a slide actuator that comprises a slider and a slide grip, the sliderbeing disposed within the first section along an inner surface of thefirst section and protruding though the slit in the first section, theslider being fastened to the slide grip that is disposed on an outersurface of the first section, wherein the frictional means includes: afriction pad positioned between the outer surface of the first sectionand the slide grip; at least one fastener that fastens the slide grip tothe slider; and a ramp, disposed on one the inner surface of the firstsection and the outer surface of the first section, that forces theslider apart from the slide grip and compresses the friction pad againstthe outer surface of the first section when the slide grip is moved awayfrom the first position.
 49. The catheter of claim 48, wherein the rampis disposed on the inner surface of the first section.
 50. The catheterof claim 49, wherein the ramp is disposed on the outer surface of thefirst section.
 51. The catheter of any of claims 1-5, wherein theactuator is movable between a first position corresponding to a firstradius of curvature of the distal end of the tip assembly and a secondposition corresponding to a second radius of curvature of the distal endof the tip assembly that is different than the first radius of curvatureof the distal end of the tip assembly, wherein the handle includes:graphical indicia, disposed on the handle adjacent the actuator,indicative of the radius of curvature of the distal end of the tipassembly in the first position.
 52. The catheter of claim 51, whereinthe handle further includes: a plurality of protrusions, disposed on atleast one of the handle and the actuator, to provide tactile feedback toa user when the actuator is moved from the first position.
 53. Thecatheter of any of claims 1-5, wherein the actuator is movable between afirst position corresponding to a first radius of curvature of thedistal end of the tip assembly and a second position corresponding to asecond radius of curvature of the distal end of the tip assembly that isdifferent than the first radius of curvature of the distal end of thetip assembly, wherein the handle includes: a plurality of protrusions,disposed on at least one of the handle and the actuator, to providetactile feedback to a user when the actuator is moved from the firstposition.
 54. The catheter of any of claims 41-53, wherein the firstposition corresponds to a neutral or rest position of the tip assembly.55. An electrophysiology catheter comprising: a handle having a distalend and a proximal end, the handle including an actuator; a flexibleshaft having a proximal end and a distal end and a longitudinal axisthat extends along a length of the shaft, the proximal end of the shaftbeing attached to the distal end of the handle; a tip assembly having aproximal end and a distal end, the proximal end of the tip assemblybeing attached to the distal end of the shaft, the proximal end of thetip assembly including a fixed bend of approximately ninety degreesrelative to the longitudinal axis of the shaft, and the distal end ofthe tip assembly including an arcuate curve having a diameter, thearcuate curve being oriented in a plane that is approximatelyperpendicular to the longitudinal axis of the shaft; and a cable,attached to the actuator and the distal end of the tip assembly, thatextends through the shaft, the cable being adapted to change thediameter of the arcuate curve in response to movement of the actuator.56. The catheter of claim 55, wherein the cable is adapted to reduce thediameter of the arcuate curve in response to movement of the actuator ina first direction.
 57. The catheter of claim 56, wherein the distal endof the tip assembly curves at least three hundred and sixty degrees inresponse to movement of the actuator in the first direction.
 58. Thecatheter of claim 56, wherein the distal end of the tip assembly curvesat least five hundred and forty degrees in response to movement of theactuator in the first direction.
 59. The catheter of claim 55, whereinthe cable is adapted to increase the diameter of the arcuate curve inresponse to movement of the actuator in a first direction.
 60. Thecatheter of claim 55, wherein the cable is a first cable that is adaptedto reduce the diameter of the arcuate curve in response to movement ofthe actuator in a first direction, the catheter further comprising: asecond cable, attached to the actuator and the distal end of the tipassembly, that extends through the shaft, the second cable being adaptedto increase the diameter of the arcuate curve in response to movement ofthe actuator in a second direction that is opposite to the firstdirection.
 61. The catheter of claim 60, wherein the diameter of thearcuate curve can be varied between approximately 3 mm and 50 mm inresponse to movement of the actuator.
 62. The catheter of claim 61,wherein the diameter of the arcuate curve in a resting statecorresponding to a neutral position of the actuator is approximately 18mm.
 63. The catheter of claim 60, wherein the diameter of the arcuatecurve in a resting state corresponding to a neutral position of theactuator is approximately 18 mm.
 64. The catheter of claim 60, whereinthe diameter of the arcuate curve can be varied between approximately 10mm and 35 mm in response to movement of the actuator.
 65. The catheterof claim 60, wherein the actuator is a first actuator, wherein thehandle further includes a second actuator, disposed on the handle, thecatheter further comprising: a third cable, attached to the secondactuator and the proximal end of the tip assembly, that extends throughthe shaft, the third cable being adapted to bend the proximal end of thetip assembly in a third direction that is perpendicular to thelongitudinal axis of the shaft.
 66. The catheter of claim 65, furthercomprising: a fourth cable, attached to the second actuator and theproximal end of the tip assembly, that extends through the shaft, thefourth cable being adapted to bend the proximal end of the tip assemblyin a fourth direction that is perpendicular to the longitudinal axis ofthe shaft.
 67. The catheter of claim 66, wherein the fourth direction isopposite to the third direction and wherein the handle further includesa third actuator, disposed on the handle, the catheter furthercomprising: a fifth cable, attached to the third actuator and theproximal end of the tip assembly, that extends through the shaft, thefifth cable being adapted to bend the proximal end of the tip assemblyin a fifth direction that is perpendicular to the longitudinal axis ofthe shaft and perpendicular to the third and fourth directions.
 68. Thecatheter of claim 66, wherein the distal end of the tip assemblyincludes a movable electrode, and wherein the handle further includes athird actuator disposed on the handle, the catheter further comprising:a fifth cable, attached to the third actuator and the movable electrode,that extends through the shaft, the fifth cable being adapted to changea position of the movable electrode along the arcuate curve of thedistal end of the tip assembly.
 69. The catheter of claim 55, whereinthe actuator is a first actuator, wherein the handle further includes asecond actuator, disposed on the handle, the catheter furthercomprising: a second cable, attached to the second actuator and theproximal end of the tip assembly, that extends through the shaft, thesecond cable being adapted to bend the proximal end of the tip assemblyin a first direction that is perpendicular to the longitudinal axis ofthe shaft.
 70. The catheter of claim 69, further comprising: a thirdcable, attached to the second actuator and the proximal end of the tipassembly, that extends through the shaft, the third cable being adaptedto bend the proximal end of the tip assembly in a second direction thatis perpendicular to the longitudinal axis of the shaft.
 71. The catheterof claim 70, wherein the first direction is opposite to the seconddirection.
 72. The catheter of claim 70, wherein the first direction isperpendicular to the second direction.
 73. The catheter of claim 55,wherein the cable is formed from a non-ferromagnetic material.
 74. Thecatheter of claim 55, wherein the distal end of the tip assemblyincludes a mapping electrode.
 75. The catheter of claim 74, wherein themapping electrode is movable along the arcuate curve of the distal endof the tip assembly.
 76. The catheter of claim 74, wherein the mappingelectrode is made from a non-ferromagnetic material.
 77. The catheter ofclaim 74, wherein the distal end of the tip assembly further includes anablation electrode.
 78. The catheter of claim 55, wherein the distal endof the tip assembly includes an electrode that can be used for bothmapping and ablation.
 79. The catheter of claim 78, wherein theelectrode is movable along the arcuate curve of the distal end of thetip assembly.
 80. The catheter of claim 55, wherein the distal end ofthe tip assembly includes a plurality of mapping electrodes disposedalong the arcuate curve of the distal end of the tip assembly.
 81. Thecatheter of claim 80, wherein the plurality of mapping electrodesproject above a circumferential surface of the distal end of the tipassembly.
 82. The catheter of claim 80, wherein the plurality of mappingelectrodes includes a tip electrode disposed at a tip of the distal endof the tip assembly.
 83. The catheter of claim 82, wherein at least oneof the plurality of mapping electrodes can also be used for ablation.84. The catheter of any of claims 55-83, wherein the distal end of thetip assembly includes a position sensor disposed in the distal end ofthe tip assembly.
 85. The catheter of any of claims 55-84, wherein thedistal end of the tip assembly includes a temperature sensor disposed onthe distal end of the tip assembly.
 86. The catheter of any of claims55-59, wherein the actuator is a first actuator, wherein the cable is afirst cable, wherein the distal end of the tip assembly includes amovable electrode and wherein the handle further includes a secondactuator disposed on the handle, the catheter further comprising: asecond cable, attached to the second actuator and the movable electrode,that extends through the shaft, the second cable being adapted to changea position of the movable electrode along the arcuate curve of thedistal end of the tip assembly.
 87. The catheter of any of claims 55-59,wherein the cable is a pull cable.
 88. The catheter of claim 55, whereinthe actuator is movable between a first position corresponding to afirst diameter of the arcuate curve and a second position correspondingto a second diameter of the arcuate curve that is different than thefirst diameter, wherein the handle includes: means for imparting a firstamount of friction on the actuator when the actuator is in the firstposition and for imparting a second amount of friction on the actuatorwhen the actuator is moved away from the first position, the secondamount of friction being greater than the first amount of friction. 89.The catheter of claim 88, wherein the handle further includes: graphicalindicia, disposed on the handle adjacent the actuator, indicative of thediameter of the arcuate curve in the first position and in the secondposition.
 90. The catheter of claim 88, wherein the handle furtherincludes: graphical indicia, disposed on the handle adjacent theactuator, indicative of the diameter of the arcuate curve in the firstposition.
 91. The catheter of claim 90, wherein the handle furtherincludes: a plurality of protrusions, disposed on at least one of thehandle and the actuator, to provide tactile feedback to a user when theactuator is moved from the first position.
 92. The catheter of claim 88,wherein the handle further includes: a plurality of protrusions,disposed on at least one of the handle and the actuator, to providetactile feedback to a user when the actuator is moved from the firstposition.
 93. The catheter of claim 55, wherein the actuator is movablebetween a first position corresponding to a first diameter of thearcuate curve and a second position corresponding to a second diameterof the arcuate curve that is different than the first diameter, whereinthe handle includes: graphical indicia, disposed on the handle adjacentthe actuator, indicative of the diameter of the arcuate curve in thefirst position.
 94. The catheter of claim 93, wherein the handle furtherincludes: a plurality of protrusions, disposed on at least one of thehandle and the actuator, to provide tactile feedback to a user when theactuator is moved from the first position.
 95. The catheter of claim 55,wherein the actuator is movable between a first position correspondingto a first diameter of the arcuate curve and a second positioncorresponding to a second diameter of the arcuate curve that isdifferent than the first diameter, wherein the handle includes: aplurality of protrusions, disposed on at least one of the handle and theactuator, to provide tactile feedback to a user when the actuator ismoved from the first position.
 96. The catheter of claim 55, wherein thehandle includes a housing, and wherein the actuator is operativelyattached to the housing, the actuator being movable between a firstposition defining a first diameter of the arcuate curve and a secondposition defining a second diameter of the arcuate curve that isdifferent than the first diameter, the handle further including:frictional means for imparting a first amount of friction on theactuator in the first position and for imparting a second amount offriction on the actuator when the actuator is moved away from the firstposition, the second amount of friction being greater than the firstamount of friction.
 97. The catheter of claim 96, wherein the housingincludes a first section that is attached to a second section, andwherein the actuator includes a thumbwheel that is positioned betweenthe first and second sections, the thumbwheel having a central boreabout which the thumbwheel rotates, wherein the frictional meansincludes: a friction disk having a central bore spaced adjacent to thethumbwheel; a shoulder nut that is received within the central bores ofthe friction disk and the thumbwheel and that attaches the friction diskand the thumbwheel to the first section; and a plurality ofcomplimentary mating features disposed on a flat surface of thethumbwheel and on a flat surface of one of the first and secondsections, that force the thumbwheel into tighter engagement with thefriction disk when the thumbwheel is moved away from the first position.98. The catheter of claim 97, wherein the flat surface of the thumbwheeland the flat surface of the one of the first and second sections eachincludes a plurality of radially spaced detents, and wherein theplurality of complimentary mating features include: a correspondingplurality of bearings secured within one of the flat surface of thethumbwheel and the one of the first and second sections.
 99. Thecatheter of claim 98, wherein each of the plurality of detents in theother of the flat surface of the thumbwheel and the one of the first andsecond sections is shaped to allow the bearings to smoothly exit thedetents when the thumbwheel is moved away from the first position. 100.The catheter of claim 96, wherein the housing includes a first sectionthat is attached to a second section, the first section including aslit, wherein the actuator is a slide actuator that comprises a sliderand a slide grip, the slider being disposed within the first sectionalong an inner surface of the first section and protruding though theslit in the first section, the slider being fastened to the slide gripthat is disposed on an outer surface of the first section, wherein thefrictional means includes: a friction pad positioned between the outersurface of the first section and the slide grip; at least one fastenerthat fastens the slide grip to the slider; and a ramp, disposed on onethe inner surface of the first section and the outer surface of thefirst section, that forces the slider apart from the slide grip andcompresses the friction pad against the outer surface of the firstsection when the slide grip is moved away from the first position. 101.The catheter of claim 100, wherein the ramp is disposed on the innersurface of the first section.
 102. The catheter of claim 100, whereinthe ramp is disposed on the outer surface of the first section.
 103. Thecatheter of any of claims 88-102, wherein the first position correspondsto a neutral or rest position of the tip assembly.
 104. A handle for usewith a catheter having an elongated shaft and a tip assembly attached toa distal end of the elongated shaft, the shaft having a longitudinalaxis that extends along a length of the shaft, and the tip assemblyincluding at least one cable for changing at least one of a shape of thetip assembly and an orientation of the tip assembly relative to thelongitudinal axis of the shaft, the handle comprising: a housing; anactuator operatively attached to the housing, the actuator beingattached to the at least one cable and movable between a first positiondefining one of a first shape of the tip assembly and a firstorientation of the tip assembly relative to the longitudinal axis of theshaft and a second position defining one of a second shape of the tipassembly and a second orientation of the tip assembly relative to thelongitudinal axis of the shaft; and frictional means for imparting afirst amount of friction on the actuator in the first position and forimparting a second amount of friction on the actuator when the actuatoris moved away from the first position, the second amount of frictionbeing greater than the first amount of friction.
 105. The handle ofclaim 104, wherein the housing includes a first section that is attachedto a second section, and wherein the actuator includes a thumbwheel thatis positioned between the first and second sections, the thumbwheelhaving a central bore about which the thumbwheel rotates, wherein thefrictional means includes: a friction disk having a central bore spacedadjacent to the thumbwheel; a shoulder nut that is received within thecentral bores of the friction disk and the thumbwheel and that attachesthe friction disk and the thumbwheel to the first section; and aplurality of complimentary mating features disposed on a flat surface ofthe thumbwheel and on a flat surface of one of the first and secondsections, that force the thumbwheel into tighter engagement with thefriction disk when the thumbwheel is moved away from the first position.106. The handle of claim 105, wherein the flat surface of the thumbwheeland the flat surface of the one of the first and second sections eachincludes a plurality of radially spaced detents, and wherein theplurality of complimentary mating features include: a correspondingplurality of bearings secured within one of the flat surface of thethumbwheel and the one of the first and second sections.
 107. The handleof claim 106, wherein each of the plurality of detents in the other ofthe flat surface of the thumbwheel and the one of the first and secondsections is shaped to allow the bearings to smoothly exit the detentswhen the thumbwheel is moved away from the first position.
 108. Thehandle of claim 104, wherein the housing includes a first section thatis attached to a second section, the first section including a slit,wherein the actuator is a slide actuator that comprises a slider and aslide grip, the slider being disposed within the first section along aninner surface of the first section and protruding though the slit in thefirst section, the slider being fastened to the slide grip that isdisposed on an outer surface of the first section, wherein thefrictional means includes: a friction pad positioned between the outersurface of the first section and the slide grip; at least one fastenerthat fastens the slide grip to the slider; and a ramp, disposed on onethe inner surface of the first section and the outer surface of thefirst section, that forces the slider apart from the slide grip andcompresses the friction pad against the outer surface of the firstsection when the slide grip is moved away from the first position. 109.The handle of claim 108, wherein the ramp is disposed on the innersurface of the first section.
 110. The handle of claim 108, wherein theramp is disposed on the outer surface of the first section.
 111. Thehandle of any of claims 108-110, wherein the ramp is symmetric.
 112. Thehandle of any of claims 108-111, wherein the first section of thehousing includes a plurality of protrusions, disposed on an outersurface of the first section of the housing, to provide tactile feedbackto a user when the slide actuator is moved from the first position. 113.The handle of any of claims 108-111, wherein the first section of thehousing includes a plurality of protrusions, disposed on an innersurface of the first section of the housing, to provide tactile feedbackto a user when the slide actuator is moved from the first position. 114.The handle of any of claims 104-113, wherein the handle furthercomprises: graphical indicia, disposed on the housing adjacent theactuator, indicative of one of the shape of the tip assembly and theorientation of the tip assembly relative to the longitudinal axis of theshaft in at least one of the first position and the second position.115. The handle of any of claims 104-114, wherein the first positioncorresponds to a neutral or rest position of the tip assembly.
 116. Ahandle for use with a catheter having a proximal end and a distal end,the catheter including at least one cable for moving a portion of thedistal end of the catheter between a first position and a secondposition relative to the proximal end of the catheter, the handlecomprising: a housing; an actuator disposed on the housing, the actuatorbeing attached to the at least one cable and movable between a thirdposition and a fourth position, the third position of the actuatorcorresponding to the first position of the portion of the distal end ofthe catheter relative to the proximal end of the catheter, and thefourth position corresponding to the second position of the portion ofthe distal end of the catheter; and frictional means for imparting afirst amount of friction on the actuator when the actuator is in thethird position and for imparting a second amount of friction on theactuator when the actuator is moved away from the third position, thesecond amount of friction being greater than the first amount offriction.
 117. The handle of claim 116, wherein the housing includes afirst section that is attached to a second section, and wherein theactuator includes a thumbwheel that is positioned between the first andsecond sections, the thumbwheel having a central bore about which thethumbwheel rotates, wherein the frictional means includes: a frictiondisk having a central bore spaced adjacent to the thumbwheel; a shouldernut that is received within the central bores of the friction disk andthe thumbwheel and that attaches the friction disk and the thumbwheel tothe first section; and a plurality of complimentary mating featuresdisposed on a flat surface of the thumbwheel and on a flat surface ofone of the first and second sections, that force the thumbwheel intotighter engagement with the friction disk when the thumbwheel is movedaway from the third position.
 118. The handle of claim 117, wherein theflat surface of the thumbwheel and the flat surface of the one of thefirst and second sections each includes a plurality of radially spaceddetents, and wherein the plurality of complimentary mating featuresinclude: a corresponding plurality of bearings secured within one of theflat surface of the thumbwheel and the one of the first and secondsections.
 119. The handle of claim 118, wherein each of the plurality ofdetents in the other of the flat surface of the thumbwheel and the oneof the first and second sections is shaped to allow the bearings tosmoothly exit the detents when the thumbwheel is moved away from thethird position.
 120. The handle of claim 116, wherein the housingincludes a first section that is attached to a second section, the firstsection including a slit, wherein the actuator is a slide actuator thatcomprises a slider and a slide grip, the slider being disposed withinthe first section along an inner surface of the first section andprotruding though the slit in the first section, the slider beingfastened to the slide grip that is disposed on an outer surface of thefirst section, wherein the frictional means includes: a friction padpositioned between the outer surface of the first section and the slidegrip; at least one fastener that fastens the slide grip to the slider;and a ramp, disposed on one the inner surface of the first section andthe outer surface of the first section, that forces the slider apartfrom the slide grip and compresses the friction pad against the outersurface of the first section when the slide grip is moved away from thethird position.
 121. The handle of claim 120, wherein the ramp isdisposed on the inner surface of the first section.
 122. The handle ofclaim 120, wherein the ramp is disposed on the outer surface of thefirst section.
 123. The handle of any of claims 120-122, wherein theramp is symmetric.
 124. The handle of any of claims 120-123, wherein thefirst section of the housing includes a plurality of protrusions,disposed on an outer surface of the first section of the housing, toprovide tactile feedback to a user when the slide actuator is moved fromthe third position.
 125. The handle of any of claims 120-123, whereinthe first section of the housing includes a plurality of protrusions,disposed on an inner surface of the first section of the housing, toprovide tactile feedback to a user when the slide actuator is moved fromthe third position.
 126. The handle of any of claims 116-125, whereinthe handle further comprises: graphical indicia, disposed on the housingadjacent the actuator, indicative of the position of the portion of thedistal end of the catheter relative to the proximal end of the catheterin at least one of the first position and the second position.
 127. Thehandle of any of claims 116-126, wherein the third position of theactuator corresponds to a neutral or rest position of the portion of thedistal end of the catheter relative to the proximal end of the catheter.128. A handle for use with a catheter having an elongated shaft and atip assembly attached to a distal end of the elongated shaft, the shafthaving a longitudinal axis that extends along a length of the shaft, andthe tip assembly including at least one cable for changing a radius ofcurvature of a distal end of the tip assembly, the handle comprising: ahousing; an actuator disposed on the housing, the actuator beingattached to the at least one cable and movable between a first positiondefining a first radius of curvature of the distal end of the tipassembly and a second position defining a second radius of curvature ofthe distal end of the tip assembly; and graphical indicia, disposed onone of the actuator and the housing adjacent the actuator, indicative ofthe radius of curvature of the distal end of the tip assembly when theactuator is in at least one of the first position and the secondposition.
 129. The handle of claim 128, wherein the graphical indiciaindicates the radius of curvature of the distal end of the tip assemblywhen the actuator is in the first position and the second position. 130.The handle of claim 129, wherein the graphical indicia further indicatesthe radius of curvature of the distal end of the tip assembly when theactuator is in at least one position intermediate the first position andthe second position.
 131. The handle of any of claims 128-130, whereinthe graphical indicia further indicates a number of circles formed bythe distal end of the tip assembly in the at least one of the firstposition and the second position.
 132. The handle of any of claims128-131, wherein the actuator is a slide actuator that comprises aslider and a slide grip, the slider being disposed within the housingalong an inner surface of the housing and protruding though a slit inthe housing, the slider being fastened to the slide grip that isdisposed on an outer surface of the housing, wherein the handle furthercomprises: a plurality of protrusions, disposed on the outer surface ofthe housing, to provide tactile feedback to a user when the slideactuator is moved from the first position.
 133. The handle of any ofclaims 128-131, wherein the actuator is a slide actuator that comprisesa slider and a slide grip, the slider being disposed within the housingalong an inner surface of the housing and protruding though a slit inthe housing, the slider being fastened to the slide grip that isdisposed on an outer surface of the housing, wherein the handle furthercomprises: a plurality of protrusions, disposed on the inner surface ofthe housing, to provide tactile feedback to a user when the slideactuator is moved from the first position.
 134. A handle for use with acatheter having an elongated shaft and a tip assembly attached to adistal end of the elongated shaft, the shaft having a longitudinal axisthat extends along a length of the shaft, and the tip assembly includingat least one cable for changing a radius of curvature of a distal end ofthe tip assembly, the handle comprising: a housing; an actuator disposedon the housing, the actuator being attached to the at least one cableand movable between a first position defining a first radius ofcurvature of the distal end of the tip assembly and a second positiondefining a second radius of curvature of the distal end of the tipassembly; and a plurality of protrusions, disposed on at least one ofthe housing and the actuator, to provide tactile feedback to a user whenthe actuator is moved from the first position.
 135. The handle of claim134, wherein the actuator is a slide actuator that comprises a sliderand a slide grip, the slider being disposed within the housing along aninner surface of the housing and protruding though a slit in thehousing, the slider being fastened to the slide grip that is disposed onan outer surface of the housing, wherein the plurality of protrusionsare disposed on the outer surface of the housing.
 136. The handle ofclaim 134, wherein the actuator is a slide actuator that comprises aslider and a slide grip, the slider being disposed within the housingalong an inner surface of the housing and protruding though a slit inthe housing, the slider being fastened to the slide grip that isdisposed on an outer surface of the housing, wherein the plurality ofprotrusions are disposed on the inner surface of the housing.
 137. Amethod of shaping a distal end of a catheter, comprising acts of:placing the distal end of the catheter in a jig, the jig including apassageway to receive the distal end of the catheter and hold the distalend of the catheter in a fixed position, the passageway defining threecontiguous regions including a first straight region formed in a firstplane, a second curved region in which the passageway bends within thefirst plane approximately perpendicularly to the first straight region,and a third curved region in which the passageway curves arcuately in asecond plane that is perpendicular to the first plane; maintaining thedistal end of the catheter and the jig at a predetermined temperaturefor a predetermined time; and removing the distal end of the catheterfrom the jig.
 138. The method of claim 137, wherein the act ofmaintaining the distal end of the catheter and the jig at apredetermined temperature for a predetermined time includes an act ofmaintaining the distal end of the catheter and the jig at a temperatureapproximately 20 degrees Fahrenheit above a sterilization temperatureused to sterilize the distal end of the catheter.
 139. The method ofclaim 137, wherein the act of maintaining the distal end of the catheterand the jig at a predetermined temperature for a predetermined timeincludes an act of maintaining the distal end of the catheter and thejig at a temperature approximately 200 to 400 degrees Fahrenheit for thepredetermined time.
 140. The method of any of claims 137-139, whereinthe act of maintaining the distal end of the catheter and the jig at apredetermined temperature for a predetermined time includes an act ofmaintaining the distal end of the catheter and the jig at thepredetermined temperature for approximately 30 minutes to an hour. 141.The method of any of claims 137-140, wherein the act of placing thedistal end of the catheter in the jig includes an act of placing afinished distal end of the catheter in the jig.
 142. The method of anyof claims 137-140, wherein the distal end of the catheter includes afinished tip assembly.
 143. The method of any of claims 137-142, whereinthe act of placing the distal end in the jig includes acts of: placingthe distal end of the catheter in a mandrel that includes thepassageway; and securing a removable retainer to the mandrel to retainthe distal end of the catheter in the passageway.
 144. The method of anyof claims 137-142, wherein the act of placing the distal end of thecatheter in the jig includes an act of placing the distal end of thecatheter in a bent tube that defines the passageway.
 145. A jig forshaping a distal end of a catheter, comprising: a mandrel having apassageway to receive the distal end of the catheter, the passagewaydefining three contiguous regions including a first straight regionformed in a first plane, a second curved region in which the passagewaybends within the first plane approximately perpendicularly to the firststraight region, and a third curved region in which the passagewaycurves arcuately in a second plane that is perpendicular to the firstplane; and a retainer removably attached to the mandrel to hold thedistal end of the catheter within the passageway.
 146. The jig of claim145, wherein the passageway is formed within a cylindrical mandrel, andwherein the first second and third regions are formed in an outercircumferential surface of the cylindrical mandrel.
 147. The jig ofclaim 146, wherein the cylindrical mandrel is formed from metal. 148.The jig of claim 146, wherein the cylindrical mandrel is formed from ahigh temperature polymer.
 149. The jig of claim 145, wherein the thirdcurved region defines at least a semicircle.
 150. The jig of claim 145,wherein the third curved region defines approximately a circle.
 151. Thejig of claim 146, wherein the retainer comprises a hollow cylinderhaving an inner diameter dimensioned to receive the cylindrical mandreland hold the distal end of the catheter with the passageway.
 152. Thejig of claim 145, wherein the passageway is formed within a disk-shapedmandrel having a first flat surface and a second flat surface, andwherein the third curved region is formed in the first flat surface ofthe disk-shaped mandrel.
 153. The jig of claim 152, wherein the retainercomprises a circular cover that is removably attached to the first flatsurface of the disk-shaped mandrel with a removable fastener.
 154. Thejig of claim 152, wherein first straight region is formed in the secondflat surface of the disk-shaped mandrel, and wherein the jig furthercomprises a tube attached to the second flat surface of the disk-shapedmandrel, an inner surface of the tube being contiguous with the firststraight region.
 155. A method of using a catheter having a handle, aflexible shaft having a longitudinal axis, and a tip assembly, the shaftbeing connected between the handle and the tip assembly, a distal end ofthe tip assembly including an arcuate curve having a diameter, themethod comprising acts of: placing the tip assembly inside a heart of apatient; and remotely, from outside the patient, adjusting the diameterof the arcuate curve.
 156. The method of claim 155, wherein the act ofremotely adjusting the diameter of the arcuate curve includes an act ofdecreasing the diameter of the arcuate curve to fit the distal end ofthe tip assembly into a blood vessel of the heart of the patient. 157.The method of any of claims 155-156, wherein the act of remotelyadjusting the diameter of the arcuate curve includes an act ofincreasing the diameter of the arcuate curve to urge the distal end ofthe tip assembly against an interior wall of a blood vessel of the heartof the patient.
 158. The method of any of claims 155-157, wherein thedistal end of the tip assembly includes at least one mapping electrode,the method further comprising an act of: mapping electrical conductivityof the heart of the patient using the at least one mapping electrode.159. The method of any of claims 155-158, wherein the distal end of thetip assembly includes at least one ablation electrode, the methodfurther comprising an act of: ablating tissue of the heart of thepatient using the at least one ablation electrode.
 160. The method ofany of claims 155-159, wherein a proximal end of the tip assemblyincludes a fixed bend of approximately ninety degrees relative to thelongitudinal axis of the shaft, and wherein the arcuate curve of thedistal end of the tip assembly is oriented in a plane that isapproximately perpendicular to the longitudinal axis of the shaft. 161.The method of any of claims 155-159, wherein a proximal end of the tipassembly includes a fixed bend of approximately a few degrees relativeto the longitudinal axis of the shaft; and wherein the catheter includesan actuator disposed on the handle and a cable that is attached to theactuator and the proximal end of the tip assembly, the method furthercomprising an act of: moving the actuator to orient the arcuate curve ofthe distal end of the tip assembly in a plane that is approximatelyperpendicular to the longitudinal axis of the shaft.
 162. A method ofusing a catheter having a handle, a flexible shaft having a longitudinalaxis, and a tip assembly, the shaft being connected between the handleand the tip assembly, a proximal end of the tip assembly including afixed bend of approximately ninety degrees relative to the longitudinalaxis of the shaft, and the distal end of the tip assembly including anarcuate curve having a diameter, the arcuate curve being oriented in aplane that is approximately perpendicular to the longitudinal axis ofthe shaft, the method comprising acts of: placing the distal end of thetip assembly inside a heart of a patient so that the arcuate curve ofthe distal end of the tip assembly contacts an inner surface of a heartvessel; and remotely, from outside the patient, applying a radiallyoutward pressure with the distal end of the tip assembly against theinner surface of the heart vessel.
 163. The method of claim 162, furthercomprising an act of: remotely decreasing the diameter of the arcuatecurve to fit the distal end of the tip assembly into the heart vesselprior to the act of remotely applying the radially outward pressure.164. The method of any of claims 162-163, wherein the distal end of thetip assembly includes at least one mapping electrode, the method furthercomprising an act of: mapping electrical conductivity of the heartvessel using the at least one mapping electrode.
 165. The method of anyof claims 162-164, wherein the distal end of the tip assembly includesat least one ablation electrode, the method further comprising an actof: ablating tissue of the heart vessel using the at least one ablationelectrode.